unusual vesical calculi of whewellite

UNUSUAL VESICAL CALCULI OF WHEWELLITE

I

By GEORGE BAKER, D.Sc. and P. L. C. GRUBB, Ph.D.

C.S.I.R.O., Mineragraphic Section, c/o University of Melbourne, Australin

I 1

I 2 1

1 3

FOUR vesical calculi from a male aged 85 are of considerable interest because of their unusual shapes and the presence on each of from seven to ten outgrowths constituted of a few mound-like (mammillary) protuberances (Fig. I , Nos. 1 and 5) and more frequent long, slender prongs or horn-like outgrowths with bifurcating (Fig. 1, Nos. 8 and 12) and trifurcating (Fig. 1, No. 4) distal ends.

Clinical features of the case were :- 1. A very large prostate (weight = 120 g.) and resultant retroprostatic pouch, 2. Gross sacculation and development of filigree bladder muscle due to prostatic obstruction, 3. Chronic retention indicating long-standing residual urine.

The four calculi were kindly made available by Mr W. Baragwanath, retired Director of the Geological Survey of Victoria, for examination of their external shape and texture and determina- tion of their internal structure and chemical composition.

One of the calculi (No. 4, Table I) was sectioned in order to elucidate optically the internal structure of the main body regions, and a portion of this specimen was utilised for X-ray, spectrographic, gravimetric, and infra-red absorption spectrophotometric investigation of its inner rather more porous central regions, and its outer more compact enveloping zones. One of the prong-like outgrowths was similarly investigated.

6 to 7 0.4426 1 1.78 I 4 to 5 0.3214 [ 1.80

1 to 3 0.4818 1.81

8 to 9

The calculi were removed from the bladder of the patient as four separate and complete entities revealing all of the mammillary and prong-like outgrowths intact. Unfortunately several of the prongs from each specimen became accidentally broken off in varying amounts (cf. Fig. 1) during the process of photographing them, prior to their receipt by us for mineralogical and chemical investigation five weeks after the operation. Attempts to re-attach broken prongs were of limited success, because some were irregularly fractured while a few were lost. Before they were accidentally broken, the shapes of the calculi were referred to as being '' sputnik-like ". The calculus sliced for the preparation of thin sections was placed in a desiccator for a few days in order to dry it out thoroughly before further treatment.

510

0.5272 1.84 [ I ____________- -

U N U S U A L VESICAL CALCULI O F WHEWELLITE

FIG. 1 (Scale is in millimetres.)

(Some of the prong-like outgrowths are missing due to accidental breakage after stone removal.) Different aspects of four calcium oxalate monohydrate calculi from the bladder of an 85-year-old male.

Nos. 1 to 3-three different vlews of the same form showing long and short, single and bifurcating outgrowths (Calculus No. 3, Table I).

Nos. 4 to 5-two separate views of a calculus with one of the slender prong-like outgrowths possessing a trifurcate distal end (Calculus No. 2, Table I).

Nos. 6 to 7-two different views of a sub-spherical calculus showing shorter mammillary outgrowths and longer prong-like outgrowths with bifurcating distal end (Calculus No. 1, Table I).

Nos. 8 to 9-two separate aspects of a calculus inddwhich the main body portion has a distinctly pyriform outline and from which there are ten outgrowths. Scars " from which some outgrowths were accidentally

broken are visible in places (Calculus No. 4, Table I). The overall porcellanous appearance of the outer surfaces of the calculi is evident in all photographs ;

occasionally the shorter mammillary outgrowths reveal a sub-vitreous lustre. Nos. 10 to 12-outgrowths accidentally broken from calculi after removal as complete entities from the

No. 11 is a single outgrowth showing thickening at its base (bottom of photograph). Nos. 10 and 12 show bifurcation at the distal ends and slight swelling at the base of the bifurcation. (Photo-

bladder.

graphed at the State Electricity Laboratories, Melbourne.)

51 1

512 B R I T I S H J O U R N A L O F U R O L O G Y

Weights and Specific Gravity Values.-The weights and specific gravity values, provided by Mr G. Baragwanath of the State Electricity Commission of Victoria, are shown in Table I .

The total weight of the four specimens is 1.7730 g. (range = 0.3214 g. to 0.5272 g.), the range in specific gravity is 1.78 to I .84, and the average specific gravity is 1 . X I .

The specific gravity for No. 4 (Table I) was independently checked by the two authors and found to agree with the originally determined value of I .84. Ordinarily the mineral is of organic origin, but where occurring as a primary mineral of hydrothermal origin in ore veins, the specific gravity of whewellite is 2.22 to 2.23.l

The lower average specific gravity value (1.81) for the whewellite vesical calculi listed in Table I , compared with the specific gravity value of whewellite of inorganic origin, is probably partly due to the porosity of the specimens as a whole, partly to traces of other materials, but principally to the probable occurrence within them of significant quantities of uncombined water (see further detail in section entitled “ Infra-red Absorption Spectra ”).

The variability in specific gravity between the four specimens of whewellite calculi is attributed largely to variations in their porosity and probable variations in the quantities of uncombined water.

Form and Dimensions.-General macroscopic examination of the specimens reveals that their main body portions are sub-spheroidal to slightly pyriform in shape (Fig. I , Nos. 3, 4 and 6) with a range in diameter from 6 mm. to 10 mm. One is more distinctly pyriform (Fig. I , No. 9) having the external dimensions of 7 mm. by 10 mm. (excluding the prongs from the measure- ments). Mr D. Lenaghan of Melbourne who removed the calculi, considered that the nearest described types are the “ jackstone ” variety. Prien and Frondel’s (1947, p. 965, Fig. 8, No. I ) illustration of a jackstone-type is vastly different in shape and appearance to that of the unique shapes under consideration.

Projections from the main body portions range from low mound-like protuberances 1 mm. long to the longer more slender prongs which measure up to 10 mm. in length. The diameters of the protuberances range from I to 2 mm., and they are approximately circular to sub-circular in cross-sectional outline.

The number of prongs and mammillary outgrowths ranges from seven to ten on the four calculi, thus :-

Seven on No. I (Table I ) . Eight on No. 2 (Table I). Ten on Nos. 3 and 4 (Table I).

They can be detected in different aspects of the calculi represented in Figure I, although some of the protuberances appear in more than one of the photographs of a particular calculus, and are thus seen from the reverse sides. Halsted (1900) has recorded five similar stones from the retroprostatic pouch of a male aged 84 years who had retention with overflow and a large prostate. Each stone had six prongs with slightly bifid tips and were also constituted of calcium oxalate. Stewart and O’Connell (1961) drew attention to this earlier work and noted the fact that three other patients with pronged stones were all over 80 years of age.

The protuberances on the more distinctly pyriform calculus (Fig. I , Nos. 8 and 9) are so arranged that six equally spaced outgrowths project in a girdle around the broader portion of the pyriform shape, and the other four are prolongations of the polar regions a t the ends of the long axis of the form, with two outgrowths a t each pole. The calculus shown in Figure I , Nos. 4and 5 , is rather similar in this respect. The outgrowths on the other two calculi are rather less regularly distributed.

The outer surface layer of each calculus has a relatively smooth but not highly polished

See Dana’s System ofMinerulogy, Vol. I l l , p. 1100, Seventh Edition, 1951.

U N U S U A L VESICAL CALCULI O F WHEWELLITE 513

appearance, with sub-vitreous lustre and porcellanous texture. The outer surface is flesh- coloured ; immediately under this surface the substance of the calculi is generally white and opaque.

The necks (i.e., proximal ends) of the mammillary outgrowths and the prongs join smoothly on to the main central body portions of each calculus (Fig. 1). At their distal ends, the longer protuberances tend to bifurcate (Fig. 1, Nos. 2, 6 and 12) and occasionally they trifurcate (Fig. 1, No. 4).

The distal ends of the mammillary outgrowths are smoothly rounded sometimes very slightly tapered (Fig. 1, Nos. 3, 5, bottom of 8, and 11) while the ends of some of the larger unbranched protuberances tend to be somewhat bulbous (Fig. 1, bottom right of No. 7). The broken ends of accidentally fractured protuberances frequently reveal an earthy (more finely crystalline), pale brown, rather porous central core, ranging from 0.5 mm. to 1 mm. across, in forms 1.75 mm. to 2 mm. in diameter, and these are surrounded by lighter coloured more compact, better crystal- lised concentric growth zones of slightly variable width and ranging up to twelve or more in number as revealed under the hand lens and binocular microscope.

The mineral matter is relatively soft, being readily scratched under light pressure when a needle is drawn across a surface revealing the concentric banding structure ; the earthy central cores are readily teased out with a fine needle-point.

Internal Structure.-Calculus No. 4 (Table 1) was split into two parts. The smallest part was used in the preparation of a thin section of approximately 30 p thickness for the purposes of examination under the petrological microscope in ordinary and polarised light (Fig. 3) ; this revealed the crystalline character of the calculus. The other part was ground down to produce a flat surface which was polished for photographing under a Leitz Panphot (Fig. 2, No. 1) ; grinding was conducted to a stage where the stumps of four of the six prongs that form an equatorial girdle around the specimen were revealed.

The generally concentric character of the growth zones as revealed under lower magnifications is shown in Figure 2, No. 1 , in which the average width of the concentric bands is approximately 60 p. The outer growth bands are continuous from the body portion of the calculus into the outgrowing prongs, and the body portion which is 8 mm. across in the polished surface (Fig. 2, No. 1) reveals at least seventy-eight alternating concentric bands of slightly different width as observed under medium powers of a binocular microscope.

Under the petrological microscope each of the broader growth zones observable under the lower powers of the binocular microscope is seen to be compounded of up to twelve narrower zones trending parallel with the outer surface of the calculus and each 5 p wide, there being approximately 20 bands per mm.

The photograph of the thin section (Fig. 3, No. 1 ) reveals the series of alternating light and darker coloured concentric bands as observed under low magnifications, with the darker bands (= opaque white oxalate), more concentrated in the core regions and in the marginal zones of the calculus. However, as shown in Figure 2, No. 1, this relationship does not always hold because frequently near the bases (proximal ends) of the prongs, the darker bands tend to transgress patchily, and partially extend along the adjoining white bands.

Examination of the relationships between these two differently coloured types of bands reveals that whereas the lighter coloured variety is very finely crystalline with randomly orientated minute crystals producing a cloudy appearance, the darker coloured bands are rather more coarsely crystalline with a well-developed radial structure (Fig. 3, No. 2). I t appears therefore that particularly in the vicinity of the bases of the prongs, there has been some recrystallisation of the lighter coloured finely crystalline material to form the darker coloured more coarsely crystalline type. This relationship is also clearly discernible within parts of the prongs (Fig. 2, No. l), although in addition, some of the ends of the broken off prongs also reveal small axial cores that are partially filled with a fine, brown powdery substance resembling dried out organic matter.

5c

514 B R I T I S H J O U R N A L OF U R O L O G Y

FIG. 2 FIG. 3 Fig. 2.-Showing internal structure of calculus.

No. 1-Smoothed surface of calculus No. 4, Table I (Nos. 8 and 9 of Fig. 1) prepared by splitting and grinding down through the central regions so as to intersect the proximal ends of four to six outgrowths present in the equatorial regions ; a fifth outgrowth occurs approximately 0.5 mm. below the plane of the photograph and is situated in the region of the patchy dark zone revealed nearly midway between the top left and top right outgrowth ( x 6). The generally lighter coloured core regions measure 5 mm. by 4.75 mm. Concentric, narrow growth bands constitute the interior regions of the calculus, and these pass smoothly into the outgrowths in the outermost zones. The internal structures of the bottom right-hand prong (distal end broken off) reveals that at an earlier stage of development the outgrowth was stumpier and mammillary

in character. No. 2-View of broken surface from near the base of a detached prong-like outgrowth with oval outline. Showing small earthy core enveloped by an outer zone of concentric light coloured bands alternating with darker brownish-grey coloured narrower bands. Radially arranged acicular crystals of calcium oxalate monohydrate are clearly discernible as the fibrous structure in the depressed fracture surface on the right

hand side of the photograph ( x 25.5). (Photographed in the Laboratories of the C.S.I.R.O. Mineragraphic Investigations Section.)

Fig. 3.-Showing internal structure of a calculus. No. 1-Photomicrograph taken in ordinary transmitted light of a thin section prepared from one side of the main body portion of calculus No. 4 (Table 1). Showing dark (opaque brownish-white in specimen) and light coloured (sub-translucent in specimen) concentric growth bands in which the light coloured bands are usually

broader ( x 12). The broken edges resulted from tearing out of the relatively soft calcium oxalate monohydrate during

preparation of the thin section. No. 2-Photomicrograph taken in polarised light under a petrological microscope of a small portion of the

thin section illustrated in Figure 3, No. 1 ( x 86). Showing fibrous radial growth structure of acicular crystals of calcium oxalate monohydrate arranged normal to the trend of the concentric growth bands. Black areas within the lighter coloured zones are calcium

oxalate monohydrate crystals in positions of extinction. (Photographed in the Laboratories of the C.S.I.R.O. Mineragraphic Investigations Section.)

U N U S U A L V E S I C A L C A L C U L I OF W H E W E L L I T E 515

X-ray diffraction, however, has shown that this is not organic matter but that it is virtually identical in composition with the predominant light and dark coloured mineral matter of the calculus and hence constituted of whewellite (calcium oxalate monohydrate).

From prong to prong it can be observed on the exposed internal portions of fractured examples that the core regions of more finely granular to earthy mineral matter vary in width relative to the overall width of the more compact outer zones of concentric bands combined. In some the inner core is approximately twice the combined width of the outer zones, in others this is reversed ; occasionally these structural units are approximately equal in width (Fig. 2, No. 2) . One broken prong revealed that the earthy core region was very much reduced in size and across the greater part of its diameter the internal structure consisted of well compacted concentric growth bands with excellent radial growth of acicular crystals. Neither the sliced body portion nor the broken ends of the outergrowths revealed the occasionally encountered cavernous interior of other forms of calculi (cf. Prien and Frondel, 1947).

The radial growth structure is more or less contiguous throughout most of the concentric bands (Fig. 3, No. 2) , and each of the longer acicular crystals is generally in optical continuity, with the trends of its longer axis normal to the trend of the bands.

The acicular crystals reveal marked twinkling effects on rotation through 90 degrees under plane polarised light ( i e . , one nicol only inserted in the optical system of the petrological microscope).

The twinkling effects arise from the marked difference between the lowest refractive index value (X = 1.491) and the highest refractive index value (Z = 1.650) possessed by the mineral whewellite. The high Z index of refraction and the strong birefringence (0-159), the oblique extinction, and the biaxial positive sign of the whewellite serve to distinguish it optically from the dihydrate of calcium oxalate (weddellite).

Structurally the calculus can be regarded overall as compound in the sense that the inner spheroidal shape with mainly whitish concentric growth zones in the core regions (Fig. 3, No. 1) is distinctly marked off from the largely darker coloured outer zone from which the mammillary outgrowths and prongs arise. This indicates development in two stages, either at two different times or in two different sites of the urinary system.

X-ray Diffraction Analyses.-Four X-ray diffraction powder analyses were obtained of the material constituting the calculi ; these were from :-

1. The core of No. 4 (Table I) calculus. 2. The outer surface layer of No. 4 (Table I) calculus. 3. The earthy substance forming the axial core of a detached prong. 4. The outer zone forming concentric bands of the same prong. Owing to the minute quantity of material available, each sample powder was microscopically

extracted and subsequently mounted by coating on a fine gelatin hair. Measurement of the d-spacings and relative intensity values showed that the four samples

were mineralogically identical and constituted of the calcium oxalate monohydrate, whewellite. X-ray diffraction traces of two common calculi constituents are shown in Figure 4.

Infra-red Absorption Spectra.-An infra-red absorption spectrophotometric analysis of No. 4 (Table I) calculus was obtained and compared with those of (1) a calculus of uric acid composition, (2) calcium oxalate, and (3) ammonium oxalate (Fig. 5), in order to test alternative factors that might be responsible for the low specific gravity values obtained for the calculi compared with the theoretical specific gravity value (2.23) of whewellite.

The possible factors influencing the anomalous specific gravity values are :- (a) Some uric acid or urates amorphous to X-rays might be present in considerable quantity

with the calculus. Uric acid (C,H,N,O,) for example has a lower specific gravity (1 -89) than the theoretical value (2.23) for whewellite (CaC,O,H,O).

516 BRITISH J O U R N A L OF UROLOGY

(6) Some amorphous hydrated whewellite might be present. (c) Some uncombined water could be present. (d) The calculus could be submicroscopically porous and despite long treatment in wetting

agents in attempts to obviate the effects of porosity, specific gravity values that are too low could still result.

The results of the analysis revealed that (a) only 1 to 5 per cent. of uric acid or urates are present in the calculus. (b) No excess of combined water was detected, thus indicating the absence of amorphous hydrated whewellite. (c) Due to masking or interference in the spectrum, it is not possible to state unequivocally whether infra-red analysis reveals a significant amount of uncombined water ; as shown later, however, it is reasonably certain that significant quantities of uncombined water are present. It is also quite feasible that much of the uncombined water could have been lost by the techniques of analysis employed inasmuch as the application of considerable pressures (9 tons/sq. in.) are required, and highly evacuated conditions are necessary during the preparation of the potassium chloride disc mounts used for containing the sample. (d ) Although it may appear doubtful whether the porosity of the sample could have resulted in experimental inaccuracies, for the reason that separate specific gravity determinations of the compact core of

6.55

URIC ACID CALCULUS

5.89 WHEWELLITE CALCULUS

L I I I 1 " " " " ' I I ' I I I ' ' l '

51 49 47 45 43 41 39 37 35 33 31 29 27 25 23 21 I9 17 I5 I3 I 1 9 7 5

DEGREES 28

FJG. 4

Fig. 4,-X-ray diffraction traces of two common calculi constituents. Uric acid (calculus-source unknown). Cu/Ni radiation. Whewellite (calculus No. 4-this study). Cu/Ni radiation.

U N U S U A L VESICAL CALCULI OF WHEWELLITE 517

W

> \ 4 1 Z I

I \

m

6

(IN 3 3 ti 3 d) 3 3 N V 1 I I W S N V 8 1

518 B R I T I S H J O U R N A L OF U R O L O G Y

the calculus and of a more porous prong from the calculus gave much the same values, it seems likely that an additional explanation for the low specific gravity value of the calculus as a whole could be submicroscopically fine porosity with very small amounts of carbon dioxide and air enclosed in micropore spaces.

Spectrographic and Gravimetric Analyses.-Because of the limited amount of material available for detailed investigations, chemical analysis of the calculus was conducted by means of combined spectrographic and gravimetric methods. Even so, of all the main components present, only the total percentage of calcium oxide could be obtained by gravimetric techniques. This resulted in a value of 30.2 per cent. CaO, whereas calculations show that the theoretical percentage should be 4 1 per cent. Furthermore, although quantitative spectrographic analysis provided reasonably reliable values (Table 11) for elements present in low concentration, the technique was of little use for evaluating the much larger quantities of calcium present. In addition, Table I1 reveals that no other elements are present in sufficient quantities to account for the abnormally low calcium content, or to provide an explanation for the low specific gravity values obtained for the calculus.

TABLE I1 Semi-quantitative Spectrographic Analyses of the Core and Outer

Marginal Zones of No. 4 (see Table I) Calculus ~ ~ ~ _ _

, Elements Detected

Calcium . Iron . Silicon . . Sodium . Titanium . Phosphorus . . Aluminium . . Magnesium . .

I

- ._ - - - -

Brownish Coloured Core

(Per cent.) 21.60 0.50

t l . 0 0 0.10 0.04 0.07 I .oo 0.06

_____-____ (p.p.m.)

i Manganese . . 1 50 Tin . 2

Whitish Outer Surface Layer with Sub-vitreous Lustre

(Per cent.) 21.60+

<0.10 t o 3 0

0.30 0.06 0.08 2.00 0.06

-

8 I- I ----

Barium. . Minute trace Minute trace Copper. . 1 Minute trace Minute trace Nickel . Minute trace Minute trace Thorium . ' : Minute trace Minute trace Uranium . Minute trace I Minute trace

Minute trace Minute trace 1 Minute trace ~ Minute trace

Vanadium . Ytterbium . I

- ~ - ~ - _ _ _ ~ _ ~ ~ _ _ _ _ -

(Anal. P. L. C . Grubb and T. H. Donnelly.)

From the results of analyses by X-ray diffraction, infra-red absorption, spectrographic and gravimetric techniques, it is concluded that the calculus investigated contains up to 26 per cent. by weight of uncombined water. Calculations furthermore show that a calculus of this composition would have a theoretical specific gravity of I .91 which is closer to the value (Table I, No. 4) obtained experimentally for this calculus ; the difference between the theoretical and actual specific gravity value obtained is probably accounted for by the submicroscopic porosity of the calculus as a whole.

U N U S U A L V E S I C A L C A L C U L I O F W H E W E L L I T E 519

Primarily to test suggestions that whewellite calculi may possess a zonal distribution in phosphate content (Buckland and Rosenberg, 1955), equal weights of sample from the core and margin respectively of No. 4 calculus (Table I) were extracted and arced in pure graphite electrodes, using a D.C. source of 3 amps. and the spectrograms were compared with those from the various dilutions of the standard rock specimens GI and WI. The results (Table 11) reveal no major zonal differentiation in the phosphate content.

The most conspicuous features of the distribution of the various elements detected (Table 11) are the relatively high iron and silica contents of the brownish coloured core regions together with a comparatively low aluminium content, while sodium is present in slightly larger amounts in the whitish outer surface layer which also contains a little more calcium. Titanium and magnesium remain at much the same level in each. Other trace elements detected, such as copper, nickel, thorium, uranium, vanadium and ytterbium are present in concentrations too low to be measured in either the core or the outer margin. Although the two spectra of different parts of calculus No. 4 were carefully scrutinised, none of the following elements could be detected : antimony, arsenic, beryllium, bismuth, boron, cerium, chromium, cobalt, dysprosium, europium, gadolinium, gold, lanthanum, lead, manganese, mercury, palladium, platinum, potassium, rhodium, silver, yttrium, zinc, and zirconium.

The indication is that if the calculi have grown over a long period of time, little change occurred in the composition of the patient’s urine during this period. Alternatively, secretion of the material constituting the stones occurred over a much shorter period of time. Whereas certain elements such as silicon, aluminium, calcium, magnesium, phosphorus, and vanadium are known to be concentrated as secretionary products in both living plants and animals (Baker, 1961 ; Baker and Jones, 1961 ; Baker, Jones, and Milne, 1961 ; Cannon, 1963) the remaining trace elements detected would probably have been precipitated as colloidal complexes from urine in a manner analogous to that outlined by Milton and Axelrod (1951). It is quite clear from the results of investigation by X-ray diffraction and infra-red absorption techniques that no organic matter remains in the calculus studied.

REMARKS AND CONCLUSIONS

Visceral obstructions in the form of relatively hard concretionary calculi are known to occur in almost all forms of the higher vertebrates. For the most part these consist of various hydrates of calcium oxalate, uric acid, and phosphates of calcium, ammonium and magnesium, with a little adsorbed carbon dioxide. Of these the monohydrate of calcium oxalate is by far the most common component of human calculi.

Among the numerous explanations advanced as the cause of calculi formation are : inadequate water intake, excess milk, carbonated drinks, hot dry climates, physical obstructions, foreign bodies, various infections, recumbency, hyperparathyroidism, metabolic factors and, formerly, the excessive use of various sulpha drugs.

A recent survey of urolithiasis in the United States of America revealed that the causes of 50 per cent. of the cases are unknown, while of the remainder, 41 -5 per cent were attributed to some form of obstruction, 47 per cent. to infection, and only 5 per cent. to metabolic factors (Buckland and Rosenberg, 1955). Lenaghan ( 1 965) has shown that only 22 per cent. of urolithiasis cases can be explained. It was also found by Buckland and Rosenberg (1 955) that urolithiasis is especially common in males between the ages of 30 and 50 years, and that whereas calculi of calcium oxalate composition are generally spherulitic in appearance, those of uric acid, calcium phosphate, and magnesium-ammonium phosphate composition assume the distinctive “ staghorn ” forms.

The very low overall phosphate content of No. 4 (Table I) calculus shows that this generalisa- tion does not always hold. Moreover in view of the phosphate deficiency, it is impossible to determine whether urolithiasis here occurred in an acid or alkaline urine, although an acid

520 BRITISH J O U R N A L O F U R O L O G Y

environment appears to be the most feasible, since this is the common condition in patients of European origin. It is nevertheless clear that owing to the deficiency in magnesium, this particular type of urolithiasis did not follow the activities of urea-splitting organisms.

Although whewellite is known to occur in both the higher vertebrates and associated with calcareous material in geological sedimentary deposits, conditions governing its precipitation in each milieu were apparently quite different.

Whereas whewellite was precipitated in geological sedimentary horizons from ionic solutions in an alkaline environment (Pecora and Kerr, 1954), in living matter the predominant medium was essentially colloidal (Milton and Axelrod, 1951). The characteristic supersaturation of colloidal solutions (in this example urine) with respect to certain elements and compounds would readily explain the regular concentric growth structure of the calculi investigated herein, since slight but regular changes in physical conditions, such as pH, within the urinary system would cause rapid precipitation of some of the colloidal material to form a further regular zone around the growing calculus.

As to the ultimate overall external form of the stones, Stewart and O’Connell (1961) considered that growth features such as projections, indentations and facets depended upon the condition of the bladder wall lying in contact with the stone and the proximity of the intravesical projection of the prostate. It is evident from this investigation that the stones grew outwards from a central nucleus by the precipitation of the relatively regular concentric bands, but little evidence has accrued that would point to the cause of initial nucleation. The fact that the brownish coloured central core regions (Fig. 2, No. 1) have a relatively high iron content, points to the possibility that nucleation was initiated by the presence of a small thrombus which was then mineralised.

The development and growth of the prongs in the four calculi examined were related to continued precipitation, from colloids, in more limited situations where axial growth could continue more favourably than growth normal to this direction. Such elongated prong-like growths were evidently formed because the bladder muscles of the elderly patient had hyper- trophied irregularly so as to produce filigree intersecting muscle strands (trabeculation and gross sacculation). Other important factors in the continued growth of these stones in the bladder are that the unusually large prostate produced a large retroprostatic pouch so that the patient retained an undue amount of residual urine for a comparatively long period of time ; conditions were therefore suited at this site to precipitation of calcium oxalate monohydrate from more concentrated solutions.

The general indication is that the inner zones of the calculi were initially precipitated in the upper urinary tract (cf. Baker, Jones, and Milne, 1961). As initially smaller smooth-walled stones (5 mm. and under), migration evidently occurred to the vesical region where further growth was of a secondary nature and where prong-growth was controlled by sacculation and the development of a filigreed bladder muscle as a consequence of prostatic obstruction.

Finally, it is of interest to note that the dimensions of the inner core (5 mm. ~ 4 . 7 5 mm.) of the calculus examined are such that it was small enough to pass down the ureter unnoticed.

The authors are indebted to Messrs W. and G. Baragwanath for providing the calculi for examination and for supplying photographs of their external form and shape. Mr D. Lenaghan kindly informed us on the location and removal of the calculi, and provided valuable data on the clinical aspects of their occurrence. Thanks are also due to Mr P. Tuckfield for agreeing to this investigation being conducted. Dr Ralph Laby of the Victorian State Laboratories carried out the infra-red absorption spectrophotometric analysis.

U N U S U A L VESICAL CALCULI O F WHEWELLITE

REFERENCES

BAKER, G. (1961). Mem. Qiieensland Mus., 14, 1. BAKER, G., and JONES, L. H. P. (1961). Nature, 189, 682. BAKER, G., JONES, L. H. P., and MILNE, ANGELA A. (1961). Aust. J. agric. Res., 12, 473. BUCKLAND, C. E., and ROSENBERG, M. (1955). J. Urol., 73, 198. CANNON, H. L. (1963). Soil Sci. 96, 196. HALSTED, W. S. (1900). “ Contributions to the Science of Medicine.” Baltimore : John Hopkins

LENAGHAN, D. (1965). Med. J. Aust., 11, 65. MILTON, C., and AXELROD, J. M. (1951). J. Mammal., 32, 139. PECORA, W. T., and KERR, J. M. (1954). Amev. Min., 39, 208. PRIEN, E. L., and FRONDEL, C. (1947). J. Urol., 57, 949. STEWART, J. 0. R., and O’CONNELL, N. D. (1961). Bvif. J. Uvol., 33, 215.

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unusual vesical calculi of whewellite

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