A neutropenic patient with haematological malignancy develops fever unresponsive to broad-spectrum antibiotics. Serum galactomannan (GM) index is 1.8 (positive cutoff ≥0.5) on two consecutive samples. Chest CT shows a new nodule with a 'halo sign'. The most likely diagnosis and first-line treatment are:

• A Pulmonary mucormycosis — liposomal amphotericin B
• B Pulmonary cryptococcosis — fluconazole
• C Pneumocystis jirovecii pneumonia — co-trimoxazole
• D Invasive pulmonary aspergillosis — voriconazole or isavuconazole ✓

Explanation

A positive serum galactomannan (a polysaccharide component of the Aspergillus cell wall) combined with the CT halo sign (ground-glass opacity around a nodule representing haemorrhagic infarction) in a neutropenic patient is highly characteristic of invasive pulmonary aspergillosis (IPA). Voriconazole (or isavuconazole) is the first-line treatment per ESCMID/IDSA guidelines. Mucormycosis produces a reverse halo (atoll) sign and GM is negative. Cryptococcosis and PCP have different CT and laboratory features.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.