Expression of Melan-A in cutaneous granular cell tumours : a diagnostic pitfall

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Morphological overlap exists between cutaneous granular cell tumours (GCT) and malignant melanoma, with the melanocyte-specific markers HMB45 and Melan-A commonly used to support the diagnosis of melanoma. We recently encountered several cases of GCT in our practice showing strong expression of Melan-A. The aim of this study was to establish the prevalence of positive immunohistochemical staining for Melan-A and HMB45 in a series of unequivocal GCTs. We also aimed to assess the prevalence of staining for PRAME (PReferentially expressed Antigen in MElanoma), a marker expressed in >80% of primary melanomas as well as many non-melanocytic tumours. A total of 20 cutaneous/subcutaneous GCTs were evaluated using Melan-A, HMB45 and PRAME immunohistochemistry. Staining for Melan-A and HMB45 was scored using a semiquantitative scale from 0 (absent) to 3+ (staining present in >50% of tumour cells). PRAME expression was recorded as either positive (>75% of cell nuclei staining) or negative. Melan-A expression was observed in four GCTs (20%), with strong and diffuse (3+) staining seen in two cases (10%), both from anogenital areas. Weak patchy nuclear PRAME expression was seen in every case, interpreted to be negative. HMB45 was also negative in all cases (100%). Our study demonstrates that Melan-A expression can be strong and diffuse in a subset of otherwise unequivocal cutaneous GCTs, which may cause diagnostic confusion with malignant melanoma. HMB45 and PRAME did not stain any of the GCTs in our series.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:56

Enthalten in:

Pathology - 56(2024), 1 vom: 22. Jan., Seite 47-51

Sprache:

Englisch

Beteiligte Personen:

Van Winden, Victoria I [VerfasserIn]
Wong, Daniel D [VerfasserIn]
Wood, Benjamin A [VerfasserIn]
Filion, Pierre [VerfasserIn]
Harvey, Nathan T [VerfasserIn]

Links:

Volltext

Themen:

Antibodies, Monoclonal
Antigens, Neoplasm
Biomarkers, Tumor
Diagnosis
Granular cell tumour
HMB45
Immunohistochemistry
Journal Article
MART-1 Antigen
Melan-A
Melanoma
PRAME
PRAME protein, human
Pathology
Transcription Factors

Anmerkungen:

Date Completed 24.01.2024

Date Revised 24.01.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.pathol.2023.09.009

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM364809108