176 ARIHRIHS Kr RHEUMATISM Vol 41, Numher 1 . January 1998, pp 176-179 0 1998, Arnerlcdn Collcgc ot Rheurnatology

RADIOLOGIC VIGNETTE

PHALANGEAL OSSEOUS SARCOIDOSIS

KAREN SMlTH and JOHN G. FORT

Clinical history

The patient, a 30-year-old African-American woman, presented with painless swelling and deformity of the left second finger and right fourth finger of several months’ duration. These signs and symptoms were asso- ciated with significant disability. Prior to the onset, her hands were normal, and she was employed as a typist. She had no other joint symptoms and denied constitu- tional symptoms such as shortness of breath, cough, fever, or weight loss.

Musculoskeletal examination findings were re- markable for swelling of the right fourth middle phalanx extending to the proximal interphalangeal (PIP) joint, as well as swelling of the left second middle phalanx. There was deformity at the PIP joints of the involved fingers. Additionally, the involved areas were warm and tender with restriction of joint motion. There were no fingernail changes. Other examination results were unremarkable with the exception of a finding of scattered, nonpruritic dark brown skin papules on her forearms.

Radiologic findings

Anteroposterior radiographs of the patient’s hands demonstrated lytic lesions on the middle phalan- ges of the left second and right fourth fingers, with significant cortical disruption and associated soft tissue swelling (Figures 1A and B). There was no reactive bone formation, periosteal reaction, or sequestrum formation. There was accompanying deformity of the fingers. The joints spaces, however, were well preserved.

Karen Smith, MD: University of Illinois at Chicago (current address: Thomas-Davis Medical Center, Tucson, Arizona); John G. Fort, MD: University of Illinois at Chicago and G. D. Searle & Co., Skokie, Illinois.

Address reprint requests to John G. Fort, MD, G. D. Searlc & Co., 5200 Old Orchard Road, Skokie, IL 60025.

Submitted for publication February 26, 1997; accepted in revised form August 18, 1997.

Diagnosis: Osseous sarcoidosis (confirmed by histopathologic demonstration of granuloma formation with rare focal caseation)

Discussion

Destructive bone lesions of the hand may be related to a number of primary or secondary causes. Clinical as well as radiographic features, such as loca- tion, presence of sclerosis, cortical disruption, periosteal reaction, and swelling, can often suggest a diagnosis. Swelling over the involved areas may be due to a number of causes, including expansion of bone, reaction of overlying soft issues, or associated soft tissue pathology such as tenosynovitis. Tissue confirmation may be re- quired in some cases of destructive bone lesions. The radiologic differential diagnosis for bony lesions of the phalanges of the hands includes a number of conditions that are listed in Table 1.

Infection is an important cause of lytic bone lesions in the hands. Osteomyelitis secondary to bacte- rial infection is usually associated with swelling. The first radiographic change in bone is periosteal new bone formation, followed by bony destruction. Skeletal tuber- culosis in the phalanges is associated with swelling, often due to expansile bone. Radiographic findings include expansion of the phalanx with thinning of the cortex, which may lead to irregular bony destruction. Sclerosis is not commonly seen in active lesions, and periosteal reaction may occur but is usually minimal (1). Atypical mycobacteria can produce similar findings. Leprosy can also produce soft tissue swelling, often associated with localized osteoporosis and destructive lesions usually of the ends of the phalanges (2). Fungal infections of the phalanges have been described but are uncommon, and include blastomycosis, coccidioidomycosis, sporotricho- sis, mycetoma, and Histoplasma duboisii dactylitis. Ra- diographic findings are generally not specific and in- clude swelling and bony lytic or destructive lesions.

Lytic lesions caused by neoplastic disorders in- clude benign and malignant primary tumors as well as

RADIOLOGIC VIGNETTE 177

Figure 1. Radiographs of the involved right fourth finger (A and C) and left second finger (B and D). A and B, At the time of presentation, there is extensive bony destruction of the phalanges, with deformity. There is no periosteal reaction, sclerosis, osteoporosis, or sequestration. C and D, Six months after the initiation of prednisone treatment, there is significant healing of bony lesions of both phalanges. Mild deformity of the digits persists.

metastatic lesions. Enchondromas, benign tumors of hyaline cartilage, are the most common bone tumors in the hand and may present as multiple, painless areas of

soft tissue swelling. Radiography demonstrates lucent defects that may deform the bone, but the cortex is generally intact (2). Osteoid osteomas are uncommon in

178 RADIOLOGIC VIGNETTE

Table 1.

Granulomatous Sarcoidosis Foreign body granulomas

Osteomyelitis Pyogenic Tuberculosis

Differential diagnosis of lytic lesions of the phalanges

Mycobacterium tuberculosis Atypical mycobacteria: Mycobacterium marinum Mycobactenurn leprae

Fungal

Benign Neoplasms and tumor-like conditions

Enchondromas Osteoid osteomas Hemangioepitheliomas Giant cell tumors Aneurysmal bone tumors

Primary: osteosarcomas Metastatic: bronchogenic tumors

Malignant

Other conditions Gout Fat necrosis in pancreatitis Hyperparathyroidism

the hands. In the fingers, they may present as a painful mass. Radiographs show different patterns depending on the origin of the nidus. The lesions may be accom- panied by pcriosteal reaction or bony sclerosis. Glomus tumors usually cause severe pain. Most often they arise in the distal finger in a periungual location. They are frequently erosive and may be accompanied by bony sclerosis. Giant cell tumors may cause painful, expansive bony lesions. They usually arise from the epiphysis. Sclerosis and periosteal reaction are uncommon unless there is associated fracture (2).

Other, uncommon causes of neoplasia-associated lytic lesions include cystic angiomatosis and heman- gioendotheliomas. Metastatic tumors of the hand are rare and generally are related to carcinoma of the lung, but other primary tumors may be responsible. The lesions are generally lytic and solitary, but may be multiple. Occasionally, foreign bodies may cause bone lesions. Radiographically, these lesions appear as lucent defects with sharply circumscribed margins. The appear- ance is often that of a benign tumor (2).

Bony lesions of the phalanges can also be seen in gout. Urate crystals may deposit in bone and appear radiographically as oval lucencies with slightly sclerotic margins. They may enlarge and break through the cortex or cause widening of bones, simulating a tumor. These lesions are often surrounded by a thin sclerotic rim that may be calcified (2).

There are a number of other uncommon causes

of phalangeal bony lesions. Radiographic findings in pancreatitis with fat necrosis may include lytic lesions (especially during the acute phase), soft tissue swelling, and, less commonly, periosteal reaction and sclerosis. Hyperparathyroidism may be associated with periosteal resorption, erosions, cystic lesions, osteoporosis, and sclerosis.

Bone involvement occurs in fewer than 10% of patients with sarcoidosis. Osseous sarcoidosis affects primarily the hands, and most commonly involves the middle and distal phalanges (2). Osseous involvement occurs primarily in patients with chronic sarcoidosis with involvement of multiple organs, and is rarely a presenting manifestation of the disease ( 3 ) . Bone lesions are frequently asymptomatic, but some patients may present with a dactylitis that is often symptomatic (4). Patients with symptoms commonly report stiffness, swelling, pain, or deformity in the involved areas. Skin lesions seem to occur more frequently in patients with bone involvement, although erythema nodosum ap- pears to be uncommon in this group. Pulmonary involve- ment also appears common in patients with osseous sarcoidosis (5 ) .

Radiographically, sarcoidosis produces a number of distinct findings. These include well-defined lytic defects in the metaphyses of the phalanges that corre- spond to the sites of nutrient foramina; well-defined, larger radiolucent defects in the phalanges, metacarpal bones, and metatarsal bones that simulate enchondro- mas; a lacework, reticulated pattern mainly confined to the metaphyses; and acro-osteolysis affecting the distal phalanges (1).

The most common finding is the reticular or lacy pattern that typically appears in the middle and proximal phalanges. It is due to cortical thinning and destruction of fine trabeculae, sparing the more conspicuous coarse trabeculae (6). The growth of sarcoid granuloma within the bone, or cytokine-mediated osteoclast resorption of bone, may lead to cystic lesions within the bone. These may appear as single or multiple lesions and may have a round or more irregular shape. Occasionally, cysts may coalesce and form large lytic lesions. These bony lesions may lead to the appearance of swelling over the involved areas (5 ) . In addition, there may be associated fractures at the involved site. Periosteal proliferation and new bone formation are infrequent except in cases of frac- ture. The absence of these findings helps distinguish osseous sarcoidosis from other conditions. Bony seques- tration is uncommon (5) . The joints are usually spared except in cases of acro-osteolysis. More importantly, the relative lack of osteoporosis even in the presence of

RADIOLOGIC VIGNETTE 179

extenyive bone destruction is important in the diagnosis of osseous sarcoidosis (1).

In considering the likely causes of our patient’s symptoms, the lack of typical features of osteomyelitis, including clinical systemic signs of infection or periosteal reaction on radiography, suggested a low probability of infection as a cause. Furthermore, the acute appearance of multiple lesions was not suggestive of a benign process. Moreover, the lack of clinical evidence for a primary tumor was not consistent with a metastatic process. Finally, the patient denied having symptoms suggestive of gout, and laboratory testing demonstrated normal uric acid levels.

Although the radiographic findings were consis- tent with osseous sarcoidosis, this case was unusual in that the presenting manifestation of sarcoidosis was de\tructive bone involvement. Other than the skin le- sions, there was no evidence for systemic sarcoidosis. Chest radiography results at presentation were consid- ered normal. Given this unusual presentation, a biopsy was performed, confirming the diagnosis of sarcoidosis.

Asymptomatic osseous sarcoidosis generally does not require therapy. Indications for therapeutic inter- vention are not well defined; however, the onset of symptoms such as pain, tenderness, or the presence of bony destruction usually indicates a need for treatment. Therapy generally consists of oral corticosteroids at a daily dosage of 15-40 mg. The dosage is adjusted according to clinical response (7). The response to Fteroids is difficult to predict. Symptom control appears to be achieved with this treatment, but radiologic im- provement may not occur (5 ) . Because of the effect on her functional status and the bone destruction, we initially treated our patient with prednisone at 30 mg/ day. This resulted in a significant reduction in swelling

and pain within 6 weeks. The prednisone was rapidly tapered and discontinued. Six months after treatment was begun, she had mild residual joint deformity and had regained most of the function of the affected fingers. Importantly, radiographs revealed healing of the lytic lesions (Figures 1C and D).

The appearance of bony lesions of the hands suggests a number diagnoses, including osseous sarcoid- osis. Clinical and radiographic features often provide important clues as to the diagnosis. In some cases a biopsy may be required to confirm the diagnosis.

ACKNOWLEDGMENTS

We thank David Karasick, MD, Department of Radi- ology, Thomas Jefferson University, Philadelphia, Pennsylva- nia, for the radiographs and for help in preparation of the manuscript. We also thank Sergio Jimenez, MD, Division of Rheumatoloa, Thomas Jefferson University, for his review of the manuscript.

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REFERENCES

Murray RO, Jacobson HG, Stoker DJ. The radiology of skeletal disorders. Edinburgh: Churchill Livingstone; 1990. Poznanski AK. Thc hand in radiologic diagnosis. Philadelphia: WB Saundcrs; 1984. Schriber RA, Firooznia H. Extensive phalangeal cystic lesions: sarcoidosis limited to the hands and feet? Arthritis Rheum 1 9 7 5 ; ~ : 123-8. Lcibowitz MR, Essop AR, Schamroth CL, Blumsohn D, Smith EH. Sarcoid dactylitis in black South African patients. Semin Arthritis Rheum 1085;14:232-7. Neville E, Carstairs LS, Gerdint James D. Sarcoidosis of bone. QJM 1911;46:215-1. Edeiken J, Dalinka M, Karasick D. Edeiken’s roentgen diagnosis of diseases of bone. Baltimore: Williams & Wilkins; 1990. Mathur A, Kremcr JM. Immunopathology, musculoskeletal fea- tures and treatment of sarcoidosis. Curr Opin Rheumatol 1993;5: 90-4.

Erratum

In the concise communication entitled “Clostridium difficile-Associated Diarrhea in Rheumatoid Arthritis Patients who are Receiving Therapy with Low-Dose Chlorambucil” published in the November 1997 issue of Arthritis & Rheumatism (Ramos et al, pp. 2090-2091), the name of the second author was spelled incorrectly. The correct spelling of the author’s name is Victor Manuel Martinez-Taboada. We regret the error.