Ultrastructural Aspects of the Dermatofibroma

Candiani, P; Rainoldi, R; Sideri, Mario; Grazie, C Le; Virgiliis, G. De; Donati, L

doi:10.1177/030089168106700316

Cited by 3 publications

(2 citation statements)

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“…The precise histotype of the lesional cells has been long debated, despite early ultrastructural analysis demonstrating fibroblastic and histiocytic cellular features. 12 In addition, until relatively recently, the nature of this lesion as a reactive process or a true neoplasm was also controversial. The identification of recurrent translocations in this tumor type has confirmed the neoplastic nature of fibrous histiocytoma: in regular fibrous histiocytoma, the fusion genes involve the protein kinase C isoformencoding PRKCB and PRKCD, with genes encoding membrane-associated proteins (PDPN, CD163, and LAMTOR1), which result in constitutive activity of PKC.…”

Section: Discussionmentioning

confidence: 99%

ALK rearrangement and overexpression in epithelioid fibrous histiocytoma

et al. 2015

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Epithelioid benign fibrous histiocytoma, also known as 'epithelioid cell histiocytoma,' has traditionally been considered a morphologic variant of cutaneous fibrous histiocytoma (dermatofibroma). In addition to its characteristic epithelioid cytomorphology, several phenotypic differences suggest that epithelioid fibrous histiocytoma may differ biologically from other variants. Recently, ALK rearrangement was described in two cases of epithelioid fibrous histiocytoma and separately in two cases reported as 'atypical' fibrous histiocytoma (with epithelioid features), with corresponding ALK expression detectable by immunohistochemistry. The goals of this study were to determine the frequency of ALK expression by immunohistochemistry in epithelioid fibrous histiocytoma, to determine its value for the diagnosis of epithelioid fibrous histiocytoma among variants and other histologic mimics, and to evaluate ALK gene rearrangement in epithelioid fibrous histiocytoma. ALK protein expression was evaluated in whole tissue sections from 33 epithelioid fibrous histiocytomas, 41 other cases of fibrous histiocytoma (11 conventional and 10 each cellular, atypical, and aneurysmal types), 10 cutaneous syncytial myoepitheliomas, and 5 atypical fibroxanthomas, using a mouse anti-ALK monoclonal antibody. Fluorescence in situ hybridization (FISH) was performed using break-apart probes. In total, 29/33 (88%) cases of epithelioid fibrous histiocytoma showed diffuse cytoplasmic ALK expression. Staining was moderate to strong in intensity in all cases except one, which showed diffuse weak expression. All other tumor types were negative for ALK expression. FISH demonstrated ALK rearrangement in all ALK-immunoreactive cases evaluated (n = 13), and not in one ALK expression-negative epithelioid fibrous histiocytoma successfully examined. In conclusion, the majority of epithelioid fibrous histiocytomas demonstrate ALK expression and ALK gene rearrangement. ALK expression is not seen in other variants of fibrous histiocytoma, providing a useful diagnostic tool to distinguish epithelioid fibrous histiocytoma from most histologic mimics. The expression of ALK suggests that epithelioid fibrous histiocytoma is a biologically distinct tumor type, unrelated to conventional fibrous histiocytoma and histologic variants. Modern Pathology (2015) 28, 904-912;

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Section: Discussionmentioning

confidence: 99%

ALK rearrangement and overexpression in epithelioid fibrous histiocytoma

et al. 2015

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“…Classic FH is composed of a variable admixture of uninucleate and multinucleate cells with a histiocytoid and/or myofibroblastic appearance. The exact histogenesis of the lesional cells is controversial, although by ultrastructural analysis the cells appear to have fibroblastic and histiocytoid features 14 . Clonal chromosomal abnormalities have been demonstrated in some FH, most commonly in the cellular subtype, suggesting that at least a subset of FH is neoplastic rather than reactive 15 .…”

Section: Discussionmentioning

confidence: 99%