Primary cutaneous epithelioid mesenchymal neoplasm with ACTB‐GLI1 fusion: a case report

Mesenchymal tumors harboring GLI1 gene abnormalities are a rare but distinctive group of neoplasms whose clinicopathologic features are currently evolving. In particular, examples of this tumor with ACTB‐GLI1 gene fusion, tentatively termed ACTB‐GLI1 epithelioid mesenchymal neoplasm (EMN), show a di...

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Bibliographic Details
Published in:Journal of cutaneous pathology 2022-03, Vol.49 (3), p.284-287
Main Authors: Rollins, Benjamin T., Cassarino, David S., Lindberg, Matthew
Format: Article
Language:English
Subjects:
ACTB‐GLI1 fusion
Actins - genetics
Aged
Case reports
CD56 antigen
Cell proliferation
Cytoplasm
Epithelioid Cells - pathology
epithelioid malignant neoplasm
epithelioid mesenchymal neoplasm
Gene Fusion
GLI1 gene
GLI1 rearrangement
Humans
Leukocytes (eosinophilic)
Male
Mesenchyme
Morphology
Neoplasia
Nucleoli
Skin Neoplasms - genetics
Skin Neoplasms - pathology
Soft Tissue Neoplasms - genetics
Soft Tissue Neoplasms - pathology
Sox10 protein
Stroma
Transcription
Tumors
Zinc Finger Protein GLI1 - genetics
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Summary:Mesenchymal tumors harboring GLI1 gene abnormalities are a rare but distinctive group of neoplasms whose clinicopathologic features are currently evolving. In particular, examples of this tumor with ACTB‐GLI1 gene fusion, tentatively termed ACTB‐GLI1 epithelioid mesenchymal neoplasm (EMN), show a distinctive monomorphic round‐to‐epithelioid morphology, nested to trabecular pattern of growth, and S100+/SOX10−/SMA– immunophenotype. We report the first case of this entity arising exclusively in the skin. A 69‐year‐old man with no prior history of neoplasia presented with a 1.5‐cm raised lesion on the left buttock. Histopathologic examination revealed a diffuse dermal proliferation of small, monomorphic, round‐to‐ovoid cells with hyperchromatic nuclei, focally enlarged nucleoli, and minimal eosinophilic to clear‐staining cytoplasm. These cells were arranged in confluent nests and trabeculae in a background of fibrocollagenous to focally myxoid stroma. Immunohistochemical analysis revealed strong positivity for S100 and CD56, and negativity for SOX‐10, SMA, Melan‐A, HMB‐45, and a variety of other markers. Based on the morphology and immunophenotype, molecular studies were performed, which revealed the presence of an ACTB‐GLI1 fusion transcript, confirming the diagnosis. Given the morphologic overlap of this tumor with other cutaneous round cell neoplasms and its potential for malignant behavior, ACTB‐GLI1 EMN is an important entity for pathologists to recognize.
ISSN:0303-6987
1600-0560
DOI:10.1111/cup.14152