Atypical Fibrous Histiocytoma: A Case Report

Case Report

Austin J Clin Case Rep. 2019; 6(5): 1159.

Atypical Fibrous Histiocytoma: A Case Report

Singer R1*, Kiziltaç K1, Etikan P2 and Erdem ZB3

¹Okmeydani Training and Research Hospital, Department of Dermatology, Istanbul, Turkey

²Dr. Akçiçek State Hospital, Department of Dermatology, Girne, Cyprus, Turkey

³Okmeydani Training and Research Hospital, Department of Pathology, Istanbul, Turkey

*Corresponding author: Ralfi Singer, Department of Dermatology, Okmeydani Training and Research Hospital, Darülaceze Cad. No: 25, 34384, Istanbul, Turkey

Received: November 25, 2019; Accepted: December 26, 2019; Published: December 31, 2019


Atypical fibrous histiocytoma is a rare variant of dermatofibroma, which may present diagnostic problems because of histopathological features, which are difficult to distinguish from a malignant tumor. The neoplasm has a tendency to recur locally and a capacity to metastasize, although very rarely. Here, we report a 46-year-old man who presented with a firm dermal nodule on the right knee. The diagnosis was made on the basis of clinical, histopathological and immunohistochemical findings. We discuss the clinical and histopathological features as well as the differentiating features of atypical fibrous histiocytoma from other cutaneous spindle cell tumors such as dermatofibrosarcoma protuberans, atypical fibroxanthoma and pleomorphic dermal sarcoma.

Keywords: Atypical fibrous histiocytoma; Dermatofibroma; Spindle cell tumors


Fibrous histiocytoma (dermatofibroma, sclerosing hemangioma, nodular subepidermal fibrosis) (FH) is a common benign cutaneous neoplasm of the skin [1]. Many histological variants of FH such as aneurysmal, atypical, cellular, epithelioid, keloidal, atrophic, hemosiderotic, lipidized, palisading, clear cell and FH with osteoclastlike giant cells subtypes have been identified over the years [1,2]. Atypical fibrous histiocytoma (AFH) is an uncommon variant of FH; the tumor is a diagnostic challenge because of histopathological features which are difficult to differentiate from a malignant tumor [1,3]. Because of this problem, it needs wider recognition in order to preclude unsuitable management. Herein, we present a case of AFH located to the lower extremity.

Case Presentation

A 46-year-old man presented to our outpatient clinic with a 5-month history of a painful, slowly growing lesion located on the right knee (Figure 1). The medical history was not remarkable. On physical examination, a 1.5cm violaceous nodular lesion with a firm consistency was noted. The lesion was totally excised and histopathological examination demonstrated spindle cells with atypical nuclei arranged in a storiform pattern in the dermis. Pleomorphic giant cells with large bizarre nuclei were noted as well (Figure 2). Immunohistochemical staining demonstrated no staining for cytokeratin, CD31, CD34, HMB 45, S-100, desmin and smooth muscle actin. Vimentin staining was not performed and Ki 67 staining showed 20% positivity. AFH was diagnosed on the basis of these findings. Since the patient was lost for follow-up, we could not perform radiologic screening to search for possible metastasis. An informed consent has been obtained from the patient to share the data in a scientific journal.