Acquired reactive digital fibroma: A clinicopathologic report of 5 cases of a new entity

Background Fibroblastic proliferations in the dermis comprise a heterogeneous group of disorders that can pose diagnostic challenges. Objective We sought to study the clinicopathologic features of this tumor. Methods We reviewed the clinicopathologic features of 5 unusual mesenchymal tumors of the digits that, to our knowledge, correspond to an entity not previously described. Results The patients were 5 men. All cases were located in the digits and were associated with history of trauma. Histopathologically, the neoplasms were located mainly in the reticular dermis. The tumors consisted of solitary nodules composed of fascicles of benign-appearing spindle cells devoid of cytologic atypia. The spindle cells formed short fascicles arranged in a haphazard manner. On immunohistochemistry, the tumor cells expressed vimentin and in 2 cases, CD34. The tumor cells were negative for smooth muscle actin (SMA), desmin, h-caldesmon, epithelial membrane antigen (EMA), S100, CD68, CD99, and beta-catenin. Limitations Only 5 cases were studied. Conclusions Awareness of this entity is of importance to avoid misdiagnosis with other conditions. Based on the immunohistochemical pattern, we believe that these tumors are fibroblastic in origin. The peculiar gross appearance and location of the lesions is clinically quite distinctive and may lead to confusion with other neoplastic and reactive processes.