September Case of the Month

Clinical History: A 52-year-old man presented to the emergency room with a history of recent-onset shivers, nausea and headache. He worked in construction and excavation. He had a history of dyslipidemia, was a non-smoker, and did not use drugs. There was no recent travel history and no exposure to birds. He was found to be tachycardic and febrile, with an elevated white blood cell count dominated by neutrophils. Pulmonary examination was unremarkable, with an O2 saturation of 92% by pulse oximetry. Screening for SARS-COV-2 was negative. Chest x-ray and CT scan showed bilateral ground-glass and reticulonodular opacities. He was treated empirically with broad-spectrum antibiotics while awaiting results of microbiological cultures, without improvement. Induced sputum culture returned positive for “filamentous fungus suggestive of Aspergillus spp”. While there was some suspicion this might have been a contaminant, antifungals were added to the antibiotics. With little clinical improvement and an unclear diagnosis, the decision was taken to perform a surgical lung biopsy for histopathologic diagnosis.

The biopsies correlated with the radiologic images, showing a diffuse micronodular pattern characterized by innumerable interstitial granulomas. The granulomas were diffusely distributed, without apparent predilection for centrilobular, paraseptal or subpleural zones, and did not directly involve vessels (Fig 1). The granulomas were well formed, with a dense neutrophilic (suppurative) center associated with fibrin and basophilic debris, surrounded by a rim of epithelioid histiocytes and occasional giant cells (Fig 2, 3). They occasionally involved small airways with ulceration of the bronchiolar epithelium and extension of the granulomatous inflammation into the airway lumen (Fig 4). In some granulomas, fragmented branching hyphal structures could be seen (Fig 5). These structures were positive on GMS (Fig 6). No other microorganisms were visible with other special stains.

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