An asymptomatic nodule on the finger

Prachi G Agrawal, Sunanda A Mahajan, Uday S Khopkar, Vidya D Kharkar

 Department of Skin and V.D, GSMC and KEM Hospital, Parel, Mumbai, Maharashtra, India

Correspondence Address:
Prachi G Agrawal
Department of Skin and V.D, GSMC and KEM Hospital, Parel, Mumbai - 400 012, Maharashtra
India

A 45-year-old female presented with a 2-month history of an insidiously growing, painless swelling on her left middle finger. There was no history of preceding trauma. Examination revealed a 15 Χ 15 mm, dome-shaped nodule with normal overlying skin, located on the dorsum of the proximal phalanx of the left middle finger [Figure - 1]. The nodule was well defined, smooth, firm, nontender, and fixed to the subcutaneous structures but not to the overlying skin. There was no pain, numbness, or stiffness of the affected digit.

Figure 1: Dome-shaped nodule with normal overlying skin on the dorsum of the left middle finger

The hematoxylin and eosin (H and E) stained section of biopsy specimen [Figure - 2]a and b revealed a well circumscribed tumor with a biphasic appearance. Moderately cellular areas of histiocyte-like cells with vesicular nuclei and foamy macrophages blended into hypocellular areas consisting of spindle cells within fibrous and hyalinized stroma. Giant cells were scattered through both the cellular and fibrous areas.

Figure 2: Biopsy from nodule showing (a) a well circumscribed tumor with a biphasic appearance (H and E, ×40) and (b) multiple giant cells (H and E, ×400)

Answer

Diagnosis

Giant cell tumor of tendon sheath

DISCUSSION

Giant cell tumor of tendon sheath is synonymous with localized nodular tenosynovitis or giant cell synovioma. ^[1] Giant cell tumors of tendon sheath are the second most common benign tumors of the hand, simple ganglion cysts being the most common. ^[2] It can present at any age but usually appears in adults aged 30-50 years, and is more common in women than in men. ^[1] Antecedent trauma is reported in a variable number of cases (1-50%). The most widely accepted theory is that it is a reactive or regenerative hyperplasia associated with an inflammatory process. ^[3]

The tumor usually presents as a firm nodule measuring from 1 to 3 cm on the hands or fingers but can also occur on the toes and other peri-articular sites such as wrist, ankle, knee, and very rarely the elbow and the hip. It has a predilection for flexor surfaces. It is typically slow growing and fixed to subcutaneous structures without attachment to the overlying skin, except on the distal fingers and toes. Although usually asymptomatic, there can be pain, numbness, or stiffness of the affected digit. The lesions may infrequently erode or infiltrate the nearby bone or rarely involve the skin. ^[1],[2]

The tumor consists of lobules of varied cellularity surrounded by dense collagen. In cellular areas, most cells are histiocyte-like with vesicular nuclei, foamy macrophages, and siderophages. Less cellular areas consist of spindle cells within a fibrous or hyalinized stroma. The characteristic giant cells resembling osteoclasts are scattered through both the cellular and fibrous areas; their cytoplasm is deeply eosinophilic and they contain a variable number of haphazardly distributed nuclei. Although mitotic figures are seen in a large proportion of cases and may be frequent, there is no evidence that mitotic activity is related to metastasis, which is an extremely rare event in these tumors. ^[1],[3]

The differential diagnosis is broad and includes rheumatoid nodule, myxoid or ganglion cyst, foreign body granuloma, tendinous xanthoma, nodal osteoarthritis, fibroma of tendon sheath, subcutaneous granuloma annulare and rare entities such as epithelioid sarcoma, synovial sarcoma and clear cell sarcoma. ^[4] Fibroma of tendon sheath is clinically similar in terms of location and microscopically resembles the hyalinised form of giant cell tumor of tendon sheath. Therefore, it is considered to represent the late stage of giant cell tumor. ^[5]

Despite the hypercellularity and large cells in this tumor, it is benign with a local recurrence rate of 30%. It can be treated by simple excision that includes a small margin of normal tissue. ^[1] The rate of recurrence depends on the presence or absence of a pseudocapsule, lobulation of the tumor, extra articular location, and the presence of satellite lesions. Radiation therapy has been reported anecdotally to be effective. ^[6]

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