Carbimazole-Induced Agranulocytosis Complicated by Multiple Lung Abscesses and Probable Aspergilloma: A Case Report

Abstract

Carbimazole-induced agranulocytosis is a rare but life-threatening adverse effect (0.1–0.5%). Although typically reversible with early detection, delayed recognition—often due to inadequate follow-up—can result in severe opportunistic infections. We report a severe and preventable complication of unmonitored therapy.

A 37-year-old woman with newly diagnosed Graves' disease was started on carbimazole 45 mg daily but defaulted to follow-up. She presented four months later with fever and pleuritic chest pain. Laboratory evaluation revealed profound agranulocytosis (WBC 210/µL; ANC ~21/µL).
Contrast-enhanced CT chest showed multiple large bilateral thick-walled cavitary lesions with air–fluid levels, consistent with lung abscesses; several cavities contained intracavitary soft tissue suggestive of fungal ball formation. Carbimazole was discontinued immediately. The patient was treated with broad-spectrum intravenous antibiotics and voriconazole. She showed clinical improvement with defervescence within five days.

This case highlights an unusually severe presentation of antithyroid drug-induced agranulocytosis complicated by extensive cavitary lung infection and probable aspergilloma—an association rarely reported. The extreme neutropenia (ANC ~21/µL) and delayed presentation
underscore the critical role of early monitoring and patient education. Most cases are preventable with timely recognition of warning symptoms and prompt blood count assessment.

Unrecognized carbimazole-induced agranulocytosis can lead to catastrophic infectious complications. Mandatory safety-netting, including explicit patient instruction regarding fever and early hematological monitoring, is essential for safe antithyroid drug use.

Bangladesh J Medicine 2026; Vol. 37, No. 2(1): pp. 234-235.