Angiomatoid fibrous histiocytoma - case series with emphasis on a late fibrotic variant.
BACKGROUND
Angiomatoid fibrous histiocytoma (AFH) is a rare, low-grade malignant, subcutaneous neoplasm in children or young adults.


METHODS
AFHs in different disease stages were studied histologically, in part, also immunohistologically, and by fluorescence in situ hybridization.


RESULTS
Depending on the degree of fibrosclerosis, nine AFH were divided into the following categories: classic type (n = 3): well-defined subcutaneous lesions composed of multinodular spindle to epithelioid (histiocytoid) cells surrounding a pseudoangiomatous space filled with blood. Peripherally, there is a fibrous pseudocapsule and an inflammatory infiltrate. Early sclerotic type (n = 4): the fibrous capsule extends more to the inner circle of the lesion, focally replacing the cellular neoplastic component and pseudoangiomatous spaces. Late sclerotic type (n = 2): the architecture of AFH with its zonal arrangement of an outer fibrous and inner cellular component is largely replaced by fibrosis occluding the pseudovascular space in the center of the lesion. Immunohistochemistry was available in 5/9 cases with positivity for EMA (5/5), desmin (3/5), caldesmon (1/2), and CD99 (2/5). One of two cases tested displayed EWSR1 rearrangement.


CONCLUSIONS
Late-stage AFH may present with marked fibrosis obscuring the real nature of the lesion and may easily be misinterpreted by the unwary as a harmless fibrotic condition.
Dermatohistological Laboratory, P.O. Box 4145, 90021, Nuernberg, Germany.
Michael
M
Wilk
Bettina G
BG
Zelger
Maria
M
Debiec-Rychter
Raf
R
Sciot
Bernhard
B
Zelger
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005355:Fibrosis / Q000145:classification / Q000378:metabolism / Q000473:pathology; D051677:Histiocytoma, Malignant Fibrous / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D008297:Male; D012878:Skin Neoplasms / Q000145:classification / Q000378:metabolism* / Q000473:pathology*
D014408:Biomarkers, Tumor