Superficial acral fibromyxoma (SAF) is a rare soft tissue benign neoplasm with a predilection for the fingers and toes tips. It usually involves the region of the nail and is presented as a slowly growing solitary nodule. Although usually confined to the dermis and subcutaneous tissue; it may occasionally involve deeper tissue .We herein report a case of SAF which developed on the tip of the 4th toe and discuss its pathological features, and broad differential diagnosis and histogenesis.
A 32-year-old healthy man was presented with a history of a nodular mass on the tip of his right fourth toe. The tumour had been present for over 9 months and had gradually increased in size. It was painful at prolonged walk. Plain radiographs of the finger were normal. The patient underwent excision of this tumor. The lesion measured 2.5 x 2.5 cm. It was well circumscribed, encapsulated, solid, and had a soft, uniform consistency. It adhered to the flexor sheath, but did not involve the joint space or body supply and was possible to dissect. Histological examination showed a lobular tumor filling the dermis and extending into the hypodermis. The neoplasm was moderately cellular, composed of spindle and stellate cells arranged in a loose storiform, partly fascicular growth pattern (Figure 1). There was no evidence of cyto-nuclear atypia, mitotic activity or necrosis. The neoplastic cells were embedded in a myxocollagenous stroma with increased numbers of small blood vessels. Scattered mast cells and neutrophils were seen throughout the lesion (Figure 2). These appearances were consistent with the diagnosis of superficial acral fibromyxoma. The immunohistochemical study showed that tumor cells stained for CD10 (Fig 3), CD99, and PS100. The CD34 and the EMA were negatives. At 18 months there was no recurrence of the tumor.
Figure 1 : Lobular tumor filling the dermis, with fascicular growth pattern, moderately cellular, composed of spindle cells (hematoxylin-eosin, original magnification x 25).
Figure 2 : Spindle and stellate cells arranged in a loose storiform, pattern embedded in a myxocollagenous stroma. (hematoxylin-eosin, original magnification x 40)
Figure 3 : CD10 show positive staining in neoplastic cells. (Immunostain x 100)
- Fetsch JF, Laskin WB, Miettinem M. Superficial acral fibromyxoma: a clinicopathologic and immunohistochemical analysis of 37 cases of a distinctive soft tissue tumor with a predilection for the fingers and toes. Human Pathol 2001; 32: 704-14.