J Pathol Transl Med.  2018 May;52(3):206-209. 10.4132/jptm.2017.11.10.

Merkel Cell Carcinoma Metastatic to Pleural Fluid: A Case Report

• Rhee YY
• Kim SH
• Kim EK
• Kim SH

• KMID: 2412936
• DOI: http://doi.org/10.4132/jptm.2017.11.10

Abstract

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine carcinoma of the skin that shows locoregional or distant metastasis. Metastasis of MCC to body cavity effusion is extremely rare; only three cases have been reported so far. Metastatic MCC in effusion cytology shows small blue round cells with fine stippled chromatin like other small blue round cell tumors such as small cell lung carcinoma or lymphoma. The diagnosis of metastatic MCC can grant patients good chances at recently advanced therapeutic options. Here, we present a case of metastatic MCC to pleural effusion with characteristic single file-like pattern.

Keyword

Carcinoma, Merkel cell; Neoplasm metastasis; Pleural fluid; Liquid-based cytology

MeSH Terms

Carcinoma, Merkel Cell*
Carcinoma, Neuroendocrine
Chromatin
Diagnosis
Financing, Organized
Humans
Lymphoma
Neoplasm Metastasis
Pleural Effusion
Skin
Small Cell Lung Carcinoma
Chromatin

Figure

• 

  Fig. 1. Chest computed tomography (CT) with cell block findings. The chest CT shows marked pleural effusion (arrows).

• 

  Fig. 2. Microscopic findings of the surgical specimen. Blue small round cell tumor with infiltrative growth (A) arranged in sheets, clusters, rows or balls, showing hyperchromatic nuclei, fine stippled or smudged chromatin and occasional mitoses (B). Immunohistochemical staining of cytokeratin 20 (C) and synaptophysin (D) show positive reaction in Merkel cell carcinoma cells.

• 

  Fig. 3. (A) Liquid based cytology (BD Surepath) of the pleural effusion (Papanicolaou stain). Malignant small blue round cells are scattered, clustered or arranged with hyperchromatic nuclei, fine granular salt and pepper chromatin, scant cytoplasm, and occasional mitotic figures. Several single file patterns with nuclear molding are characteristic (arrows). (B) The cell block findings are similar to those in liquid based cytology’s. Immunohistochemical staining of cytokeratin 20 (C) and synaptophysin (D) in the cell block of pleural effusion.

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