The pathological distinction between “Deep penetrating” dermatofibroma and dermatofibrosarcoma protuberans

Abstract

In selected cases, the clinicopathological distinction between deep penetrating dermatofibroma (DPDF), which involves the subcutis, and dermatofibrosarcoma protuberans (DFSPs) may be challenging. In most instances, attention to the cytological constituency of the lesions and the overall architecture is sufficient to make this separation. DPDF is typified by cellular heterogeneity, including giant cells and lipidized histiocytes; when it extends into the hypodermis, it does so either using the interlobular subcuticular fibrous septa as scaffolds or in the form of broad pushing fronts of tumor. In contrast, DFSP is a cytologically monotypical tumor, which entraps subcutaneous adipocytes diffusely or grows in stratified horizontal plates in the hypodermis. In the minority of cases where conventional morphological analysis of optimal biopsy specimens is diagnostically indeterminate, immunostaining for CD34 and factor XIIIa (FXIIIa) is helpful; it is also often necessary when a poorly-representative sample of the lesion has been obtained by the clinician. Characteristically, DF is diffusely FXIIIa-reactive and CD34-negative, whereas DFSP manifests the converse of those findings. Other markers such as Ki-M1p, mutant p53 protein, and metallothionein may also provide adjuvant diagnostic information in this context, as may the observation of abnormalities in chromosomes 17 and 22 by direct karyotypic analysis.

Childhood dermatofibrosarcoma protuberans: Role of preoperative imaging

“…In contrast, the tumor of DFSP diffusely entraps adipocytes of the subcutis or invades by stratified horizontal plates. 19 Immunohistochemical findings reveal Factor XIIIa positivity and CD34 negativity for DF and Factor XIIIa negativity and CD34 positivity for DFSP. Stromelysin 3, a member of the metalloproteinase family, may also be used to distinguish a DF from DFSP with positively stained cells in DF and negatively stained cells in DFSP.…”

“…Gutierrez et al 16 The main conditions in the histopathologic differential diagnosis of congenital or childhood DFSP include infantile myofibromatosis, fibrous hamartoma of infancy, giant cell fibroblastoma (GCF), and deep penetrating DF. 18,19 Infantile myofibromatosis, characterized by dermal and subcutaneous nodules of myofibroblasts appearing at birth or in early infancy, may be solitary or multicentric. The solitary type involves the skin, muscle, and bone whereas, the multicentric type may have visceral involvement.…”

CD34+ Pigmented Fibrous Proliferations: The Morphologic Overlap Between Pigmented Dermatofibromas and Bednar Tumors

“…16 Lesions that demonstrate features of both dermatofibromas and DFSPs are well described. 7,[17][18][19] As in our cases, these lesions can have epidermal changes, a storiform pattern within the lesional cells, abutment of the subcutaneous fat, and expression of CD34. Separating these so-called indeterminate fibrous histiocytomas from true DFSP may be possible with cytogenetic analysis.…”

Deep Penetrating Fibrous Histiocytoma

“…7 In comparison, DFSP is cytologically monotypic and entraps subcutaneous adipocytes in the hypodermis. Immunohistochemical studies are useful in distinguishing DPFH from DFSP.…”