Superficial CD34-positive fibroblastic tumor in the forearm of a middle-aged patient: A newly described, rare soft-tissue tumor

Abstract

Superficial CD34-positive fibroblastic tumor is a recently described soft-tissue tumor entity. A 48 year-old-male presented with a gradually increasing soft-tissue mass in his right forearm of 2 years' duration, along with multiple subcutaneous soft-tissue nodular lesions, and reminiscent of lipomas over his body. He underwent a wide excision of his forearm mass. Microscopic sections showed a circumscribed tumor in the dermis and subcutaneous fat, composed of spindle cells, inflammatory cells, including lymphocytes, plasma cells, and eosinophils, along with interspersed markedly pleomorphic giant cells containing moderate-to-abundant "glassy" cytoplasm, vesicular nuclei, exhibiting prominent nucleoli, and intranuclear pseudoinclusions. There were no significant mitotic figures, areas of hemorrhage, necrosis, or pigment histiocytes. By immunohistochemistry, the tumor cells were diffusely positive for CD34 while negative for cytokeratin (CK), pan CK (AE1/AE3), S100 protein, CD30, and CD31. MIB1/Ki-67 was low and highlighted 4%-5% tumor nuclei. Diagnosis of superficial CD34-positive fibroblastic tumor was offered. Sections from the various resection margins were free of tumor. Postresection, the patient is alive with no evidence of disease for the past 8 months. This constitutes as one of the first case reports of this rare tumor entity from our country. Its diagnostic and treatment implications are discussed herewith.

Superficial CD34 Positive Fibroblastic Tumour, A Mesenchymal Tumour with Borderline Malignant Potential: A New Entity

“…[1,9] Diagnosis of Pleomorphic Hyalinizing Angiotectic Tumor (PHAT) is based on presence of hyalinized vessels which may show thrombosis along with stromal hyalinization. [2,10] All such features were absent in our case. Synovial sarcoma (SS) usually arises in deep soft tissue of the upper and lower limbs and is also seen in head and neck region.…”

“…[3] This slow growing tumour occurs in middle aged adults with a mean age range of 20 to 76 years and has a slight male preponderance. [2][3][4] The most common sites of predilection in descending order are: lower limbs, shoulders, buttock and upper limbs. This mesenchymal tumour of borderline malignant potential has some distinct morphological features which made it to be classified as a separate entity.…”

“…The various differential diagnoses of this tumour include-atypical fibroxanthoma, myxofibrosarcoma, undifferentiated pleomorphic sarcoma, fibrosarcoma arising in a dermatofibrosarcoma protuberance (DFSP), epithelioid sarcoma, pleomorphic hyalinising angiotectic tumour, synovial sarcoma, epithelioid leiomyosarcoma, atypical fibrous histiocytoma, solitary reticulohistiocytoma, hemosiderotic fibrolipomatous tumour and pleomorphic rhabdomyosarcoma and granular cell tumor. [1,2,4] Atypical fibroxanthoma resembles SCD34FT morphologically but more commonly the former is located in dermal region and is mitotically more active with atypical mitosis. On IHC, atypical fibroxanthoma is positive for CD10 and negative for CD34, [4] as opposed to our case.…”

“…Both these features are absent in SCD34FT. [2] Pleomorphic rhabdomyosarcoma involves deep soft tissue ie. skeletal muscles and morphologically, shows marked pleomorphism with multinucleated giant cells.…”

“…The neoplastic spindle cells are arranged in fascicles and storiform pattern with tumour cells showing striking nuclear and cellular pleomorphism, but by contrast, possess low mitotic activity. [1,2] On immunohistochemistry, this recently proposed entity shows diffuse vimentin and CD34 positivity with few cases showing focal CK expression.…”