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Published on: June 7, 2019
BAP1-Inactivated Melanocytic Tumors With Distinctive p16-Negative Clonal Growth and Liver Metastases
Benjamin A Wood1,2, Sarah Shepard3, Craig James3
1PathWest Laboratory Medicine, J Block, QEII Medical Centre, Perth, Western Australia, Australia.
Abstract:
BAP1-inactivated melanocytic tumor (BIMT) represents a distinct subtype of melanocytoma, with characteristic morphologic features. These lesions are associated with inactivation of the BAP1 tumor suppressor gene. Although there are frequently histologic features that might otherwise cause concern for malignancy, including enlarged cells with nuclear variability, prominent nucleoli, and a lymphocytic inflammatory infiltrate, empirical data suggest that the majority behave in a clinically benign fashion. We report 2 cases of cutaneous BIMT with a distinctive morphologic pattern of clonal expansion with p16 loss. In both cases, there was liver metastasis after complete excision, in the absence of locoregional recurrence. These rare cases highlight the possibility of a distinct pathway of malignant progression in BIMT.
Insights
BAP1-inactivated melanocytic tumors (BIMT), often appearing concerning, usually behave benignly. However, rare cases show malignant progression with metastasis, suggesting a distinct pathway.
Area of Science:
- Oncology
- Dermatopathology
- Genetics
Background:
- BAP1-inactivated melanocytic tumor (BIMT) is a melanocytoma subtype linked to BAP1 tumor suppressor gene inactivation.
- Histologic features can mimic malignancy, yet most BIMTs exhibit benign clinical behavior.
Purpose of the Study:
- To describe two rare cases of cutaneous BIMT with a specific morphologic pattern.
- To investigate the potential for malignant progression in BIMT.
Main Methods:
- Histopathologic examination of cutaneous BIMT.
- Analysis of p16 loss and clonal expansion.
- Clinical follow-up for locoregional recurrence and distant metastasis.
Main Results:
- Two cases of cutaneous BIMT demonstrated clonal expansion with p16 loss.
- Both cases experienced liver metastasis following complete surgical excision.
- No locoregional recurrence was observed in either case.
Conclusions:
- These cases suggest a distinct malignant progression pathway in BIMT.
- BIMT, despite its typical benign course, can rarely metastasize.
- Further research is needed to understand BIMT's malignant potential.
