Superficial CD34-positive fibroblastic tumor

Last revised by Tom Foster on 28 Jul 2023

Superficial CD34-positive fibroblastic tumors (SCPFT) or PRDM10-rearranged soft tissue tumors are rare low-grade mesenchymal neoplasms of the dermis and subcutis 1-3 that have been just recently added to the WHO classification of soft tissue tumors in 2020 2,3.

Superficial CD34-positive fibroblastic tumors are rare with less than 200 reported cases in the literature 4,5. They have been found in a wide age range ranging from 8 to 76 years and median age of 33 years (less than 10% of patients ≤18 years of age). Men are slightly more commonly affected 4.

The diagnosis of superficial CD34-positive fibroblastic tumors is established by location, histological and immunohistochemical criteria 1,2.

Diagnostic criteria according to the WHO classification of tumors: soft tissue and bone (5th edition) 2:

  • superficial location

  • abundant granular to glassy eosinophilic cytoplasm

  • very low mitotic count but considerable nuclear pleomorphism

  • diffuse immunoreactivity to CD34 and frequent positivity of cytokeratins

Superficial CD34-positive fibroblastic tumors usually present as painless longstanding slow-growing dermal or subcutaneous masses usually <5 cm in size 1,3.

Superficial CD34-positive fibroblastic tumors are superficial sheet-like or fascicular proliferation of spindle and epithelioid cells with remarkable cell atypia but insignificant mitotic activity 1-4.

The etiology of superficial CD34-positive fibroblastic tumors is currently unknown 2.

Tumors are most commonly located in a suprafascial location of the extremities more often in the lower ones including the thigh, arms, buttocks, shoulder and vulva 1,2.

Macroscopically tumors are well-defined with a yellow-tannish color, at times gelatinous appearance and a firm consistency 1,2.

Histologically superficial CD34-positive fibroblastic tumors display the following characteristics 1-4:

  • cellular sheets and fascicles of spindled or epithelioid cells

  • extensive eosinophilic cytoplasm often with a glassy or granular appearance

  • compelling nuclear pleomorphism

  • insignificant mitotic activity

  • rare necrosis

  • common mixed inflammatory infiltrates

Immunohistochemistry stains express CD34 and are often positive for cytokeratins in up to 70% of cases 1-3.

PRDM10 rearrangements have been reported in a subset of several cases 1,2,5.

At the time of writing, there are only very few reports of the radiological features of this entity 6.

The tumor has been described as well-delineated in one case with weak contrast enhancement. The pictures depicted the entity as a hypodense lesion compared to skeletal muscle 6,7.

The tumor has been characterized as a well-circumscribed lesion. An internal lobulated appearance has been demonstrated 7.

  • T1: hypointense (mildly hyperintense compared to muscle)

  • T2: hyperintense

  • T1 C+ (Gd): mild enhancement

The radiological report should include a description of the following:

  • form, location and size

  • tumor margins

  • relation to muscular fasciae

  • relationship to local nerves and vessels

  • local lymph nodes

Management consists of surgical excision. Prognosis is excellent with very rare cases of lymph node metastases and rare local or distant recurrences 1-4.

Superficial CD34-positive fibroblastic tumors were first described by the American pathologists Jodi M Carter, Sharon W Weiss, Konstantinos Linos, David J DiCaudo and Andrew L Folpe in 2013 1,4.

Conditions that can mimic the presentation and/or the appearance of superficial CD34-positive fibroblastic tumors include the following:

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