Pulmonary mycoses diagnosed using exfoliative cytology: infection or colonization?

Flexible bronchoscopy with exfoliative cytology is an important tool for the diagnosis of pulmonary fungal infections. The question of colonization versus true fungal infection is of critical importance.

A 5-year retrospective analysis of all cases of pulmonary fungal infection diagnosed using exfoliative cytology was performed. Clinical, radiological, bronchoscopy and histopathology findings were recorded.

A total of 69 cases of mycoses were retrieved. The most common fungal organism identified was Aspergillus followed by Candida and Pneumocystis. Most cases of Aspergillus and Candida in cytological specimens presented as a pulmonary mass or endobronchial growth and were diagnosed as carcinomas in biopsy specimens, thus representing colonization. All cases of Pneumocystis with bilateral ground glass infiltrates and cryptococcosis with parenchymal mass lesion in radiology represented true infection. Histoplasma was identified in pleural fluid from a known case of lung carcinoma.

Aspergillus and Candida species are the most common fungal organisms. Most of these represent colonization of malignant growths. However, true fungal infections may also present as mass lesions and may masquerade malignancy clinically. Fluid cytological examination is an important diagnostic modality for pulmonary mycoses; however, it is important to correlate results with clinical, bronchoscopy and biopsy findings for accurate diagnosis and appropriate management.