Histoplasmosis of the Head and Neck Region Mimicking Malignancy: A Clinic-Pathological Predicament

Objective: Histoplasmosis is a systemic, deep mycotic infection caused by Histoplasma capsulatum. Disseminated histoplasmosis (DH) is synonymous with HIV seropositive immunocompromised individuals; however, isolated histoplasmosis involving the head and neck mucosal sites mimicking malignancy is a clinical predicament. The result, in a superficial biopsy with marked pseudoepitheliomatous hyperplasia (PEH), in a tertiary care cancer center where the number of squamous carcinomas far outnumber the infectious diseases, could be catastrophic. Material and Method: The archives of a tertiary care cancer hospital were searched (2010-2019) for cases of histoplasmosis involving the head and neck mucosal sites in HIV non-reactive patients. Results: Six cases of isolated head and neck histoplasmosis were seen in biopsies from 4 men and 2 women, with an age range of 46-72 years. Three of these patients suffered from chronic illnesses. The most common site involved was the larynx (vocal cords) in three cases, two cases were involving lips, and one involving the tongue. The biopsies were reviewed in-house with a clinical diagnoses of malignancy in all and an outside biopsy diagnosis of “squamous cell carcinoma” in 2 cases. The important histological findings in the biopsy were PEH (3 cases), granulomas (2 cases), lymphoplasmacytic inflammation (all cases). Eosinophils were conspicuous by their absence. Intracellular histoplasma was seen in all cases, albeit to varying density, which was confirmed with GMS stain. Conclusion: A high index of suspicion, meticulous history taking by oncologists, and appropriate distinction of PEH from neoplastic squamous proliferation by pathologists in superficial biopsies and an apropos deeper wedge biopsy are essential to clinch the correct diagnosis.