Cytological Spectrum of Pulmonary Histoplasmosis Diagnosed by Bronchoalveolar Lavage: 12 Years of Experience in French Guiana

Abstract

Disseminated histoplasmosis is a major cause of mortality in HIV-infected patients. Rapid and efficient diagnosis of Histoplasma capsulatum is crucial. Cytopathology is available in most hospitals and represents a rapid diagnostic alternative. In this study, we reviewed 12 years of experience to describe the cytology of histoplasmosis diagnosed by bronchoalveolar lavage (BAL) in relation to patient characteristics. BAL-diagnosed pulmonary histoplasmosis concerned 17 patients (14 HIV+). BAL cellularity ranged from 76,000 to 125,000 cells/mL in HIV patients, and 117,000 to 160,000 cells/mL in non-HIV patients. Macrophages predominated in all HIV patients (from 60% to 88%), lymphocytic infiltrates ranged from 5% to 15%, and neutrophils were very heterogeneous (from 2% to 32%). The number of H. capsulatum at hot spots seemed greater in HIV-infected than in immunocompetent patients (9 to 375 vs. 4 to 10) and were inversely proportional to the CD4 counts. Yeasts were both intracellular and extracellular in 85.7% of the HIV patients. This is the most comprehensive series detailing the cytological aspects of BAL in the diagnosis of H. capsulatum, focusing on the number of yeasts and their clustering pattern. The cytological examination of the Gomori-Grocott-stained BAL allows a reliable diagnosis of histoplasmosis.

Multiple infections in an immunocompromised patient—How cytology can help

“…Cytological assessment of a BAL can be very helpful in identifying various organisms, and in determining their distribution pattern and background 8 . The precise typing of a fungus by cytology alone will not always be possible, as the organisms mentioned above show overlapping features.…”

“…Cytological assessment of a BAL can be very helpful in identifying various organisms, and in determining their distribution pattern and background. 8 The precise typing of a fungus by cytology alone will not always be possible, as the organisms mentioned above show overlapping features. In hindsight, Histoplasma could have been considered earlier, especially if there had been knowledge of previous travels of the patient.…”

Is Micro and Nanotechnology Helping Us Fight Histoplasmosis?

“…Upon spores' inhalation, the mycelial form goes through a dimorphic transition to yeast to infiltrate the host macrophages in almost any organ, granting its intracellular replication and survival [15][16][17]. Researchers have proved that the H. capsulatum yeasts facility on colonizing and adhering to different organ cryosections (lung, spleen, liver, gut, and trachea) is due to a well-known survival strategy of microorganisms: biofilm formation [18][19][20].…”

“…The disease severity spectrum ranges from asymptomatic or mild lung disease to severe pneumonitis with respiratory compromise, depending on inoculum amount, exposure intensity, and host's immunity [9,14,15].…”

“…In fact, disseminated histoplasmosis among AIDS patients is a rapidly progressing, lifethreatening illness that requires prompt treatment with antifungal medication [6]. In Latin America, histoplasmosis is often listed as the number one death cause in patients with advanced AIDS [15].…”