Objective: To study the clinicopathologic characteristics, immunophenotype and differential diagnosis of superficial acral fibromyxoma (SAF).
Methods: The clinical, pathologic and immunohistochemical features of a case of SAF occurring in left middle finger was studied, with review of literature.
Results: The patient was a 62-year-old male who presented with a solitary painful nodule located in the distal aspect of his left middle finger. The nodule lied close to the nail bed and deep to the underlying periosteum. Grossly, the tumor was poorly circumscribed, measured 2 cm in greatest dimension and had a greyish-white cut surface and rubbery consistency. On low-power examination, the tumor was centred in the dermis and displayed a vague lobular pattern. The tumor cells were spindled to stellate in shape and associated with myxoid matrix. Focal fascicular or loose storiform patterns were also noted. A delicate vascular network was identified in the myxoid stroma. Mast cells were readily observed. On high-power examination, the tumor cells were relatively bland-looking and showed at most a mild degree of nuclear atypia. Mitotic figures were rare and coagulative tumor necrosis was absent. Immunohistochemical study showed that the tumor cells were positive for vimentin, CD34 and CD99. Focal staining for CD10 was also demonstrated. Other immunomarkers including actins, desmin and epithelial membrane antigen were negative.
Conclusions: SAF is a distinctive soft tissue tumor occurring mainly in the digits of adults. Awareness of this entity is helpful in distinguishing SAF from other myxoid soft tissue tumors occurring there. Complete excision with clear resection margins is the mainstay of treatment.