Primary cutaneous solitary fibrous tumor with entrapped eccrine components

Abstract

First described in the pleura, solitary fibrous tumor (SFT) was subsequently reported in a variety of organ systems. Compared to other anatomic sites, primary cutaneous and superficial SFTs are relatively rare. Although several histopathologic variants of cutaneous and superficial SFT have been described, a primary cutaneous SFT harboring glandular components has not hitherto been documented in the literature. The current case report describes a spindle cell neoplasm of the right finger in a female patient with characteristic morphologic and immunohistochemical features of a SFT. Unexpectedly, various glandular and ductal components were identified in the SFT. A few hyperplastic lobules of sweat glands demonstrating similar morphology as the intratumoral glandular components and composed of secretory coils displaying mucinous metaplasia and ducts were detected in the attached subcutaneous tissue, suggestive of an inductive or obstructive effect of the SFT on the eccrine units. The intratumoral glands and ducts were judged to represent entrapped benign eccrine components from the attached subcutaneous tissue. Since this variant of SFT with entrapped eccrine components could mimic many biphasic epithelial and stromal tumors, pathologists should be aware of this unusual variant of SFT to avoid potential erroneous diagnosis, particularly mistaken confusion with a biphasic synovial sarcoma.

Subcutaneous Solitary Fibrous Tumor: A Case Report

“…NAB2-STAT6 fusion genes are specific for SFT, but this cumbersome resource is often unavailable and the immunohistochemistry for STAT6 is utilized in daily practice [2]. The strong nuclear STAT6 immunoreactivity, highly sensitive and specific for SFT, allowed to rule out the differential diagnosis with other CD4-positive tumor [1,2,[4][5][6][7]. Besides STAT6, the main tumor markers were CD34, CD99, and Bcl-2 expressions [2,4].…”

“…The solitary fibrous tumor (SFT) is a mesenchymal neoplasm with irregular fascicles of spindle cells, staghorn-like blood vessels, collagen, and 0 to 10/high-power fields [1][2][3][4][5][6][7][8]. This tumor more often has a low risk, even in some cases with malignant histology [1,4].…”

“…SFTs are found in people of all ages, being more often described in adult females [1][2][3][4]. They are more recognized in the pleuropulmonary region, and also found in meninges, gastrointestinal tract, bone, liver, kidney, thyroid, parotid, soft tissues, and skin [1][2][3][4][5][6][7][8]. Differential diagnosis with CD4-positive dermatofibrosarcoma protuberans or spindle cell lipoma may be challenging, mainly in the presence of one SFT variant [1,2,5,7,8].…”

“…They are more recognized in the pleuropulmonary region, and also found in meninges, gastrointestinal tract, bone, liver, kidney, thyroid, parotid, soft tissues, and skin [1][2][3][4][5][6][7][8]. Differential diagnosis with CD4-positive dermatofibrosarcoma protuberans or spindle cell lipoma may be challenging, mainly in the presence of one SFT variant [1,2,5,7,8]. We present the case of a young woman with unsuspected SFT located on supra-pubic subcutis, aiming to enhance the suspicion index about this very uncommon condition.…”

Cutaneous solitary fibrous tumor: Report of three cases with review of histopathological mimics

“…2 SFT is less commonly reported in the skin. [3][4][5][6][7][8][9][10][11][12][13][14] Variable histopathological features, overlap with other spindle cell tumors, and superficial skin biopsies confound diagnosis. SFT is usually hypercellular and consists of spindled cells in focally hyalinized stroma with pericytomatomatous vessels.…”