Merkel Call Carcinoma
Merkel cell carcinoma (MCC) is a rare, aggressive carcinoma arising from cutaneous neuroendocrine cells. The high rate of recurrence, aggressive behaviour and propensity for early metastasis justify the need for early detection methods and treatment .
MCC is most frequently located on the head and neck areas, followed by the extremities. Clinically, they usually present as asymptomatic, rapidly growing, red-shiny nodules or as red, mildly scaly plaques . Sometimes, superficial ulcerations can occur.
Few studies describe the dermatoscopic structures found in MCC, the prevalent feature being a polymorphous vascular pattern. The absence of pigmented structures and blue-grey veil has been constant throughout the literature published so far.
Previously described as milky-red globules and clods by Dalle et al, these structures are patognomonic of malignant tumours, with the exception of pyogenic granuloma. The main differential disgnosis includes hypo- and amelanotic melanoma and rarely BCC.
Single vascular patterns, as well as two or more vascular patterns recognized in the same lesion have been described. Vascular morphology consisted in dotted, linear straight, linear serpentine, arborizing and glomerular vessels on a pink-white background.
An intraepithelial bowenoid and pagetoid proliferation of oblong hyperchromatic epithelioid cells with high mitotic rate, small nucleoli and scant cytoplasm were described by Navarette et al , features characteristic of a neuroendocrine tumour. Immunohistochemistry was positive for CK20, INSM1 and chromogranin and a subset of cells was positive for CK7 and EMA. Merkel cell polyomavirus (MCPyV) was negative.
- Dalle et al.: Dermoscopy of Merkel cell carcinoma. Dermatology 2012;224:140-4. PMID: 22487601. DOI.
- Sadeghinia et al.: Can dermoscopy open a new way to diagnosing Merkel cell carcinoma?. Int J Dermatol 2019;58:e68-e71. PMID: 30675720. DOI.
- Jalilian et al.: Clinical and dermoscopic characteristics of Merkel cell carcinoma. Br J Dermatol 2013;169:294-7. PMID: 23574613. DOI.
- Harting et al.: Dermatoscopic vascular patterns in cutaneous Merkel cell carcinoma. J Am Acad Dermatol 2012;66:923-7. PMID: 21978573. DOI.
- Cinotti et al.: Dermoscopic and reflectance microscopy features of primary and metastatic Merkel cell carcinoma: Ten cases. Skin Res Technol 2019;25:407-409. PMID: 30593691. DOI.
- Navarrete-Dechent et al.: Dermoscopy and reflectance confocal microscopy of intraepidermal Merkel cell carcinoma. Australas J Dermatol 2021;62:238-241. PMID: 33216952. DOI.
- Zalaudek et al.: How to diagnose nonpigmented skin tumors: a review of vascular structures seen with dermoscopy: part I. Melanocytic skin tumors. J. Am. Acad. Dermatol. 2010;63:361-74; quiz 375-6. PMID: 20708469. DOI.