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Melanocytic Neoplasm With KITand APCMutations: A New Subtype of Melanocytoma?
- Source :
- The American Journal of Dermatopathology; February 2024, Vol. 46 Issue: 2 p107-110, 4p
- Publication Year :
- 2024
-
Abstract
- We report a very unusual case of melanocytic neoplasm appearing clinically as a 0.5-cm dome-shaped pigmented papule on the chest of a 63-year-old man. Microscopically, it was an asymmetric, entirely dermally based neoplasm characterized by a multinodular, vaguely plexiform architecture composed of moderately pleomorphic spindled melanocytes with ample, dusty pigmented cytoplasm and scattered multinucleated cells. The tumor cells were strongly positive for Melan-A, HMB45, S100, and PRAME, whereas p16 showed diffuse nuclear loss. β-catenin presented a strong and diffuse cytoplasmic staining, while nuclei were negative. Despite an increased cellularity, mitotic count was low (1/mm2). Fluorescence in situ hybridization revealed no copy number alteration in melanoma-related genes (CDKN2A, MYB, MYC, CCND1and RREB1). DNA and RNA sequencing identified KITc.2458G>T and APCc.6709C>T mutations. No further genetic alteration was detected including TERT-promoter (TERT-p) hot-spot mutation. A re-excision was performed. A sentinel lymph node biopsy was negative. Clinical investigations revealed no extracutaneous involvement. The patient is disease-free after a follow-up period of 8 months. Given the peculiar morphologic and molecular findings, we hypothesize the lesion may represent a novel subtype of an intermediate grade melanocytic tumor (melanocytoma).
Details
- Language :
- English
- ISSN :
- 01931091 and 15330311
- Volume :
- 46
- Issue :
- 2
- Database :
- Supplemental Index
- Journal :
- The American Journal of Dermatopathology
- Publication Type :
- Periodical
- Accession number :
- ejs65616960
- Full Text :
- https://doi.org/10.1097/DAD.0000000000002556