APIMC223889222 - CME/CMLE - Merkel Cell Carcinoma in Pleural Fluid-APIMC223889222

APIMC223889222 - Educational Activity

Pdf Summary

This educational commentary by Dr. Padmini A. Manrai, a Gynecologic Pathology Fellow, focuses on the identification and differentiation of Merkel cell carcinoma (MCC) cells within pleural fluid, based on a case of a 72-year-old male with worsening shortness of breath, who has a medical history of multiple conditions including MCC.<br /><br />Pleural effusions, seen in this patient, are categorized into transudates or exudates based on parameters such as protein and lactate dehydrogenase (LDH) levels. This exercise aims to help participants distinguish between malignant cells and normal cells in pleural fluids.<br /><br />Merkel cell carcinoma is a rare neuroendocrine skin cancer. When it metastasizes to the pleural cavity, it forms highly cellular fluids composed mainly of small blue cells. MCC cells feature a high nuclear to cytoplasmic ratio and typically have a narrow rim of light blue cytoplasm. Characteristic inclusions in these cells, known as intermediate filament buttons, give the nuclei a kidney-shaped appearance. These cells may also show clefting, grooving, and multi-lobation, and they frequently exhibit binucleation and multinucleation.<br /><br />The commentary details the features of various cells found in pleural fluids:<br />- Malignant cells are identified by specific nuclear and cytoplasmic characteristics.<br />- Atypical mitotic figures show abnormal chromatin distribution, providing clues to malignancy.<br />- Mesothelial cells have dense cytoplasm with a 'lacy skirt' appearance.<br />- Activated macrophages possess foamy or vacuolated cytoplasm.<br />- Neutrophils can be seen with multilobated nuclei and cytoplasmic granules.<br /><br />The analysis of bodily fluids, which includes microscopic examination and measurements like protein and LDH levels, is key in diagnosing and managing pleural effusions accurately. Identifying the unique features of MCC in pleural fluids is essential for rapid, preliminary diagnostics, which can be confirmed through immunohistochemical stains.<br /><br />This summary aids in understanding the relevance of microscopic and physiological assessments in diagnosing pleural effusions related to malignancy.

Keywords

Merkel cell carcinoma

pleural fluid

malignant cells

cytoplasmic characteristics

neuroendocrine skin cancer

microscopic examination

immunohistochemical stains

pleural effusions

mesothelial cells

diagnostics