Case Report J Clin Ultrasound 19578-582, Novemberinecernber 1991 Not subject to copyright within the United States.

CCC 0091-2751/91/090578-05 Published by John Wiley & Sons, Inc.

Sonography of Plantar Fibrornatosis

Mark Reed, DPM;* Gretchen A. W. Gooding, MD;? Suzanne M. Kerley, MD;t Melanie S. Himebaugh-Reed, DPM* and Virginia J. Griswold, MDt

This report describes the first sonographic de- scription of plantar fibromatosis of the foot in the ultrasound literature. It defines how ultrasound was used to determine the extent of the mass and how it may have potential to detect recur- rence.

The French surgeon Dupuytren, in 1832, was the first to identify the palmar aponeurosis as the affected structure in contractures of the hand and was the first to describe an associated foot condition involving the plantar fascia.' Plantar fibromatosis, which has been reported to affect 1% to 2% of the general population,2 has also

From the Departments of *Podiatry, tRadiology, and $Plastic Surgery, Veterans Administration Medical Center, San Francisco, California. For reprints contact Gretchen A. W. Gooding, MD, Department of Radiology (114), San Francisco VA Medical Center, 4150 Clement Street, San Francisco, California 94121.

been reported in association with penile fibroma- tosis (Peyronie's disease), knuckle pad thicken- ing, and keloid f~ rma t ion .~

CASE STUDY

A 42-year-old, white male construction worker who presented with a recurrent painful mass on the plantar arch area of his left foot complained of constant, severe pain with walking and stand- ing. No knuckle pad thickening or palmar, pe- nile, or right foot involvement was noted.

Sonography performed six months before sur- gery (Figure 1) revealed a hypoechoic nodule of uniform consistency localized superficial to the medial slip of the plantar fascia measuring 1.1 cm x 0.5 cm. A 2.3 cm x 1.5 cm nodule was lo- cally excised from the same area after the conser- vative treatment consisting of wearing custom- molded shoe insoles and a course of intralesional

FIGURE 1. Initial preoperative ultrasound examination: Longitudinal scan through the medial plantar aspect of the foot, using a 5-MHz linear array transducer and a stand-off pad, demonstrates a well-defined, hypoechoic nodule localized superficial to the medial slip of t h e plantar fascia (arrows), measuring 1.0 cm x 0.5 cm (demarcated by X and +).

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PLANTAR FIBROMATOSIS 579

FIGURE 2. (A1 Eleven months after initial surgery. Follow-up ultrasound examination using a 5-MHZ linear array transducer reveals, on longitu- dinal scan, an elongated, well-defined, hypoechoic, homogeneous mass localized superficially along the medial slip of the plantar aponeurosis (arrows) measuring 4.8 cm x 1.7 cm X 0.6 cm (demarcated by +). (B) Magnetic resonance images obtained 11 months after initial surgery, at the same time as the ultrasound images shown in Figure lB, using a 1.5 Tesla superconducting magnetic resonance imaging system and surface receiver coil. This figure demonstrates, in a T,-weighted coronal image (TR 600 TE 15), a mass (arrow) of intermediate to low signal intensity located along the medial plantar aspect of the left foot that interrupts the linear, low signal intensity of the plantar aponeurosis. The image of the opposite foot is presented for comparison.

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580 CASE REPORT: REED ET AL.

FIGURE 3. Gross specimen after a wide en bloc type excision of the lesion, including the full-width portion of plantar fascia surrounding the lesion, a 2 cm area of plantar fascia proximal and distal to the lesion, and a 5 cm x 2 cm area of overlying skin.

FIGURE 4. Pathologic study of the surgical specimen reveals islands of rnyofibroblasts lacking in cytologic pleomorphism that are aligned with the surrounding collagen fibers and have a high cell to collagen ratio. Also present is a longitudinally transected vessel (arrow) with stratified, hobnail-like endothelial cells. Hematoxylin and eosin stain (magnification X100).

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steroid injections had failed. Plantar fibromatosis was diagnosed by pathologic examination. Eight months after surgery, the ultrasound examina- tion again demonstrated a hypoechoic nodule of similar size (1.0 cm x 0.4 cm).

Eleven months after surgery, the subepideral mass beneath a visible scar was mildly erythe- matous, severely tender, firm, lobulated, nonmo- bile, and measured 5 cm x 2 cm x 1 cm. Radio- graphs were negative. Sonography, using both 5-MHz and 10-MHz linear array transducers Acuson, Mountain View, CA; Picker Micorview, Highland Heights, OH), revealed a hypoechoic, homogeneous mass localized superficial to the central band and medial slip of the plantar fascia measuring 4.8 cm x 1.7 cm x 0.6 cm (Figure 2A). The 5-MHz transducer provided a wider field of view. The 10 MHz had a water-path in- terface.

Magnetic resonance imaging revealed a mass localized superficial to the plantar fascia (Figure 2B). Magnetic resonance imaging of the lesion was obtained in a high-field strength magnet us- ing a surface coil. Both TI and T2 weighted im- ages were obtained in the axial and coronal planes (Figure 2B). On the TI weighted images, the plantar aponeurosis had a low signal inten- sity, and the plantar fibromatosis had an inter- mediate to low signal intensity similar to that of muscles and was seen as an ovoid mass occurring along the plane of the plantar aponeurosis. In the T, weighted images, the mass continued to have an intermediate to low signal intensity and the plantar aponeurosis a low signal intensity. Neither study showed evidence of invasion of the mass into the deeper plantar musculature.

At surgery, a wide en bloc excision was per- formed of the lesion, adjunct plantar fascia, and the overlying skin (Figure 3). No evidence of ex- tension of the tumor into the deeper musculature was noted. However, a significantly large sen- sory nerve of approximately 0.3 cm in diameter was found embedded into the center of the mass (not seen by ultrasonography or magnetic reso- nance imaging) and was subsequently severed and buried under muscle. With a drain in place, primary closure was achieved in layers. The path- ologic diagnosis was recurrent plantar fibromato- sis (Figures 3 and 4). The patient healed without incident and has had no recurrence to date.

DISCUSSION

Although no clear predisposing factor has been elucidated for plantar fibromatosis, heredity is involved in some cases.' Trauma, in varying de-

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grees, may be an important aggravating factor but not a cause of the di~ease. ' ,~ The disease has been associated with epilepsy' and al~oholism.~

The onset of the disease can occur at birth, childhood, or throughout all decades of life, with the majority of cases occurring in the fourth de- cade of life. Usually, involvement of both feet oc- curs, with only one foot being sympt~matic.~ The distribution for the disease has been variably re- ported with a slight predominance for men and C a ~ c a s i a n s . ~ . ~ The rate of recurrence of plantar fi- bromatosis is about 65% and the recurrence of the lesion after surgery can occur immediately or up to two years, with one year being the a ~ e r a g e . ~ ' ~

Plantar fibromatosis usually presents clini- cally as a nonmobile, asymptomatic, irregular- shaped, single or multinodular lesion located in the longitudinal medial arch area of the plantar surface of the f o ~ t . ~ , ~ Progression of the lesion has been associated with varying degrees of pain, erythema, edema, and hyperkeratotic skin over the lesion. Microscopically, the lesion is characterized as a proliferation of well-differenti- ated hyperplastic, fibroblast-like cells, or myofi- broblasts having an aggressive clinical behavior with an infiltrative pattern of growth and usu- ally an abundance of proliferating cells between the collagen fibers. Pathologically, plantar fibro- matosis has been classified into three stages: the proliferative phase, the involutional phase, and the residual phase-all of which can be identi- fied in a single histologic specimen. Deep muscle invasion can occur, but only after surgical exci- sion and recurrence of the disease. However, me- tastases have never been r e p ~ r t e d . ~

Since both plantar and palmar fibromatoses are unencapsulated, have upon recurrence an es- pecially aggressive local presentation, are usu- ally extremely cellular, and have some mitotic figures, the misdiagnosis of a malignant neo- plasm has o ~ c u r r e d . ~ , ~ A differential diagnosis for plantar and palmar fibromatoses should in- clude musculoaponeurotic fibromatosis (desmoid or deep aggressive fibromatosis), fibrosarcoma, synovial sarcoma, liposarcoma, malignant mela- noma, Kaposi's sarcoma, fibroma, lipoma, lipo- blastoma, epidermal inclusion cyst, neurofi- broma, neurolemmoma, ganglion, chondroma, keloid scarring, and inflammatory reaction to a foreign body.7 Musculoaponeurotic fibromatosis, which has a high recurrence rate (57%),4 can usually be distinguished from a plantar or pal- mar fibromatosis by the presence of a large solid mass, erosion of either the metatarsal or meta- carpal bones or other neighboring bones, and the absence of a contracture if in the hand.4 High-

582 CASE REPORT: REED ET AL.

grade malignancies of the plantar sole region are extremely rarea3

Sonography has the unique ability to distin- guish cystic masses from solid masses, to dis- criminate circumscribed lesions from diffuse in- filtrating lesions, and to delineate in the foot the relationship of a mass to the plantar fascia, which is noted as a bright linear interface ap- proximately 5 mm to 8 mm from the surface of the sole. Furthermore, sonography has the added flexibility and ease of examining the foot using a handheld transducer, and the distinct asset of combining longitudinal and transversely ori- ented scans to accurately localize the lesion in three dimensions.8 High-resolution transducers in a linear array configuration are superior to sector instruments because of their better near- field characteristics.

From the application of sonography in this case, the plantar fibromatosis was determined to be superficial to the plantar fascia, uniformly consistent in texture, and the size and location of the lesion was accurately elucidated (Figure 1A and B). This information was subsequently com- bined with the clinical findings to refine the sur- gical approach and extensiveness of the opera- tion.

Magnetic resonance imaging was useful for lo- calization of the lesion along the plantar aponeu- rosis in three planes, and for tissue differentia- tion based on the signal characteristics of the T, and T, weighted images. The opposite foot was also scanned for comparison. The tissue planes were respected. The plantar aponeurosis was readily identified as a linear structure of low sig- nal intensity in both T, and T2 weighted images.

The use of standard radiographic films of the sole of the foot was noted to be ineffective in ap- preciating the plantar fibromatosis.

The nonoperative treatment for plantar fibro- matosis has involved reassurance of the patient, using custom-made shoes or shoe insoles to ac- commodate the lesion, the controversial use of intralesional steroid injections, oral administra- tion of alpha-tocopherol, and the controversial use of radiation the rap^.^,^ Surgical excision of

the lesion is indicated when the nodules become enlarged, painful, or d i ~ a b l i n g . ~ > ~ Generally, an en bloc type of excision usually encompassing 0.5 cm of surrounding, normal-appearing plantar fascia is indicated.6 Recurrence of the lesion has been attributed to an inadequate resection of the mass by trying to resect the lesion off the plantar fa~cia.~Jj Usually, resection of a major portion of the plantar fascia results in little functional loss to the ~ a t i e n t . ~ Rarely is total plantar fasciot- omy necessary or indicated.6 However, as with all surgery on the plantar aspect of the foot, wound dehiscence, neuroma formation, infection, delayed healing, and recurrence of the lesion may increase the morbidity of the surgery.

This report demonstrates that sonography can define the lesion of plantar fibromatosis, and can determine not only progression but also whether or not the lesion is limited to the tissues superfi- cial to the plantar aponeurosis, which is an im- portant factor in prognosis.

REFERENCES

1. Dupuytren G: De la retraction des doigts par suite d’une affection de l’aponevrose palmaire, descrip- tion de la maladie, operation chirurgicale qui con- vient dans des cas. J Uniu Med Chir Paris 51831- 1832.

2. Larsen RD, Posch JL: Dupuytren’s contracture: With special reference to pathology. J Bone Joint Surg 40A:773,1958.

3. Allen RA, Woolner LB, Ghormley RK: Soft-tissue tumors of the sole. J Bone Joint Surg 37A:14, 1955.

4. Coulson WF: Surgical Pathology 2 ed. J B Lippin- cott, New York, 1988, p 1216.

5. Crenshaw AH (ed): Campbell‘s Operative Ortho- paedics. CV Mosby, St Louis, Mo, 1987, p. 809.

6. McGlamry ED: Comprehensive Textbook of Foot Surgery. Williams and Wilkins, Baltimore, MD, 1987, p 619.

7. Kirby EJ, Shereff MJ, Lewis MM: Soft-tissue tu- mors and tumor-like lesions of the foot. An analysis of eighty-three cases. J Bone Joint Surg 71A:621, 1989.

8. Fornage BD, Rifkin MD: Ultrasound examination of the hand and foot. Radiol Clin North Am 26:109, 1988.

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