Chih-Yi Liu 1 2, Nai-Wen Kang 3, Kengo Takeuchi 4 5 6, Shih-Sung Chuang 7
Affiliations
- Division of Pathology, Sijhih Cathay General Hospital, New Taipei City 221, Taiwan.
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City 221, Taiwan.
- Division of Hemato-Oncology, Department of Internal Medicine, Chi-Mei Medical Center, Tainan 710, Taiwan.
- Division of Pathology, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan.
- Pathology Project for Molecular Targets, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan.
- Department of Pathology, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan.
- Department of Pathology, Chi-Mei Medical Center, Tainan 710, Taiwan.
ABSTRACT
Merkel cell carcinoma (MCC) is a rare primary neuroendocrine carcinoma (NEC) of the skin. As compared to pure MCCs, combined MCCs are aggressive and exhibit a higher probability of metastasis. A correct diagnosis might be missed, especially when the biopsy sample is too small or too superficial. We report a 79-year-old Taiwanese male who presented with lymphadenopathy suspicious for lymphoma. A nodal biopsy showed metastatic NEC. A skin tumor in the lower back was identified, and an incisional biopsy showed only squamous cell carcinoma (SCC). A subsequent excisional biopsy was performed based on the advice of the senior pathologist because of the presence of metastatic nodal NEC. Finally, a diagnosis of combined MCC and SCC was confirmed. Our literature review identified 13 cases of combined MCC with nodal metastasis as initial presentations, all with an aggressive clinical course. Both the MCC and non-MCC components could be present in the metastatic nodes. Metastases of pure MCC cells were observed in three combined MCCs in sun-protected areas, probably pointing to a distinct pathogenesis. Excision or punch biopsy to include the deep dermal NEC component is recommended as timely diagnosis is mandatory for appropriate management of patients with this rare skin cancer.
Keywords: Merkel cell carcinoma; Merkel cell polyomavirus; cytology; paranuclear blue inclusion; skin cancer; thyroid transcription factor-1.
>Diagnostics (Basel). 2023 Jan 26;13(3):449. doi: 10.3390/diagnostics13030449.