[Mesenchymal tumors of the skin. Atypical fibrous histiocytoma]

Clinicopathological features of superficial CD34-positive fibroblastic tumor

BACKGROUND

Superficial CD34-positive fibroblastoma (SCPFT) is a newly discovered mesenchymal tumor characterized by high polymorphism, low mitotic rate, and diffuse CD34-positive reactions.

AIM

To further determine the clinicopathological features of SCPFT.

METHODS

We retrospectively analyzed the clinicopathological data, immunohistochemistry results, and differential diagnoses of four patients with SCPFT and performed a literature review. Relevant fusion genes were also detected.

RESULTS

The tumors were all located in the lower extremities and presented as slow-growing painless masses located in the dermis and subcutaneous tissue. Microscopically, the tumors were composed of spindle-shaped to epithelioid cells with scattered abnormal and pleomorphic nuclei on a fibrous or fibromyxoid background. Necrosis was not found in the tumor tissues, and mitotic figures were rare. Immunohistochemically, the tumor cells were strongly positive for vimentin and CD34, and CKpan showed focal positivity in two tumors. All four patients were followed (13-57 mo, mean 35 mo), and one patient experienced local recurrence.

CONCLUSION

SCPFT is a newly discovered borderline mesenchymal tumor that can locally recur or even metastasize. Familiarity with its clinicopathological features will help avoid confusion with skin mesenchymal tumors with similar features.

Atypical cutaneous fibrous histiocytoma: an unusual and misleading variant of fibrous histiocytoma

Atypical fibrous histiocytoma is a distinctive variant of cutaneous fibrous histiocytoma, which is often mistaken histologically for sarcoma and which have a tendency to recur locally and a capacity to metastasize, although very rarely. We report a new case of atypical cutaneous fibrous histiocytoma in a 31-year-old man who presented with a recurrent polypoid nodule on the abdominal wall. The diagnosis was made on the basis of morphological and immunohistochemical findings. We discuss through this case and a review of the literature pathological and evolutive features and diagnostic difficulties of this entity.