Anthracotic pigment in pleural fluid: A case report

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Article, Peer-reviewed

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BACKGROUND: The presence of anthracotic pigment (carbon) in pleural fluid cytologic samples is unusual and to date has only been reported in individuals who are crack (freebase cocaine) smokers. We report the cytologic finding of carbon-laden macrophages in pleural fluid unrelated to crack abuse. CASES: Two patients were identified with anthracotic pigment within their pleural fluid on cytologic review; an 88-year-old human immunodeficiency virus (HIV)-negative man with a transudative effusion and a 46-year-old HIV-positive man with a history of crack abuse who presented with an exudative effusion. Dense black pigment within macrophages was identified in both the ThinPrep slide and cell block material. This pigment failed to stain for iron and was present within the cytoplasm of KP-1 immunoreactive and TFF-1 negative macrophages. CONCLUSION: Carbon-laden macrophages can be found in exudative and transudative pleural effusions and may be seen without any relationship to crack abuse. Because this finding may be secondary to a subclinical pneumothorax, its identification and reporting may be of clinical significance.

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