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Intraepidermal Merkel cell carcinoma with no dermal involvement
1Department of Pathology and Laboratory Medicine/Faculty of Medicine, University of Calgary, Alberta, Canada.
The American Journal of Dermatopathology
|March 4, 2000
Summary
We report a rare case of Merkel cell carcinoma (MCC) exclusively confined to the epidermis. This finding supports the theory that MCC originates from Merkel cells and may indicate a better prognosis for this specific variant.
Area of Science:
- Dermatology
- Oncology
- Pathology
Background:
- Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer primarily affecting the dermis.
- Epidermal involvement in MCC is uncommon, with only one prior case of exclusively intraepidermal MCC reported.
Observation:
- A 74-year-old man presented with a 2.0-cm verrucous papule on his left index finger.
- Biopsy and excision revealed a wholly intraepidermal pagetoid MCC with significant epidermal hyperplasia and atypia, but no dermal invasion.
Findings:
- Immunohistochemical analysis confirmed MCC, showing diffuse cytoplasmic staining for cytokeratin 20 and negative results for other markers.
- The tumor cells exhibited florid pagetoid spread throughout the epidermis, with no evidence of dermal tumor cells.
Implications:
- This case provides evidence for an intraepidermal variant of MCC, supporting the hypothesis of Merkel cell origin in some cases.
- An exclusively intraepidermal MCC may represent a distinct clinical entity with a potentially more favorable prognosis compared to dermal MCC.