You are asked to see a patient in the Bone Marrow Transplantation Unit for fever, neutropenia and pleuritic pain. The patient, a 45-year-old woman, had an allogeneic stem cell transplant five weeks ago for acute leukemia. She has been receiving prophylaxis with acyclovir and fluconazole.
Three days ago she developed fever without localizing signs or symptoms. At that time, she had failed to engraft and remained neutropenic with an ANC of zero.
Cefepime was begun. Fever persisted and vancomycin was added.
On day 5 of fever, she complained of right-sided pleuritic pain. She has no cough.
A chest CT scan showed a peripheral right-sided lung lesion which was described by the radiologist as having a “ halo sign,” that is, a nodular dense consolidation with hazy ground glass infiltrate surrounding it.
Which one of the following is the most likely cause of the lung problem?
Aspergillosis
Candidiasis
Legionellosis
Bronchiolitis obliterans
This halo sign is very suggestive (but not diagnostic) of aspergillosis or, less commonly, mucormycosis. Aspergillus species can form a “halo sign” (central dense consolidation surrounded by ground glass infiltrate) seen in Figure A below because they invade and thrombose blood vessels. The nodule is fungus and infarcted lung; the halo is due to hemorrhage into the alveoli. Halo signs occur early in infection and last only a few days. The other diseases listed would be unusual causes of a halo sign in a neutropenic patient.