Cutaneous CD34+ Spindle Cell Neoplasms: Histopathologic Features Distinguish Spindle Cell Lipoma, Solitary Fibrous Tumor, and Dermatofibrosarcoma Protuberans

Abstract

Spindle cell lipoma (SCL), dermatofibrosarcoma protuberans (DFSP), and solitary fibrous tumors (SFT) are cutaneous CD34+ spindle cell tumors that may exhibit histopathologic and immunophenotypic overlap. We sought ways to reliably distinguish among these lesions even in small or superficial biopsies. Ten morphologic characteristics were analyzed in a group of 5 SCLs, 6 cutaneous SFTs, and 12 DFSPs. SFT and DFSP exhibited extensive histopathologic overlap in small or partial biopsies. However, adnexal entrapment, defined as diffuse proliferation of tumor cells around pilosebaceous and eccrine structures with minimal disruption or expansion of the dermis, was a feature seen in 10 of the 12 DFSPs and in none of the SFTs or SCLs. Even when only superficial portions of a lesion were present, this feature was identifiable. Spindle cell lipomas posed little diagnostic difficulty, in part because excisional biopsies were performed in all cases of SCL. The number of samples included in the study is relatively small, in part due to the rarity of cutaneous solitary fibrous tumors. We conclude that careful attention to these histopathologic features enables reliable distinction among these tumors.

Spindle cell lipoma of the mandibular mucogingival junction: a case report of unusual oral neoplasm

“…15 In the present case, tumor cells exhibited immunoreactivity for CD34 and bcl-2, and not for SMA and desmin. Moreover, spindle cells were negative for S-100, while mature adipocytes were strongly positive for.…”

Application of COL1A1–PDGFB fusion gene detection by fluorescence in situ hybridization in biopsy tissue of dermatofibrosarcoma protuberans

“…In the immunophenotypic panel, although CD34 immunoreactivity is particularly useful for distinguishing DFSP from other fibrohistiocytic lesions, its expression may be markedly reduced or completely negative in a small minority of tumors, such as in conventional cases (cases 11 and 21), myxoid subtypes (cases 1 and 23) and many cases of FS‐DFSP . Importantly, other CD34‐positive tumors, including vascular tumors and solitary fibrous tumors, could also result in misdiagnosis . Further molecular diagnostic methods should be helpful in distinguishing difficult cases of DFSP from other spindle cell lesions.…”

A Rare Case of Spindle Cell Lipoma of Nose

“…The spindle cells stain positive for CD34 with androgen receptors in men and usually adipocytes stain positive for S-100. [7] The variable proportion of fibrous and myxoid elements among different example of these tumors confers to spindle cell lipoma a variable microscopic appearance that can make the diagnosis difficult. [8] These tumors do not have the tendency to recur.…”