Aspergillus vs Mucorales
How to tell Aspergillus and Mucorales apart when a board question makes them look alike.
Aspergillus is septate acute-angle hyphae and cavity/neutropenia disease; Mucor is broad right-angle hyphae with DKA and necrotic eschar.
Side by side
Aspergillus causes allergic bronchopulmonary disease, fungus balls in cavities, or invasive pneumonia in neutropenia with septate acute-angle branching hyphae.
Mucorales cause rapidly invasive rhino-orbital-cerebral or pulmonary disease in diabetic ketoacidosis, neutropenia, or iron overload with broad right-angle hyphae.
Aspergillus conidia are inhaled and hyphae can invade vessels, especially when neutrophil defenses are impaired.
Mucorales are angioinvasive molds that cause thrombosis, infarction, necrosis, and black eschars in high-risk hosts.
Septate acute-angle hyphae, galactomannan, halo sign, aspergilloma, or ABPA findings support Aspergillus.
Broad ribbon-like pauciseptate right-angle hyphae, black nasal eschar, orbital invasion, and DKA support mucormycosis.
The trap
Both can be angioinvasive molds, so hyphal morphology and host risk carry the answer.
Watch it explained
Test it nowThe repair move
For invasive molds, read the hyphae and host risk before reading the organism name.
Try a free question
CoreA 52-year-old woman 18 days into induction chemotherapy for acute myeloid leukemia has an absolute neutrophil count of 80 cells/uL. She develops fever, pleuritic chest pain, and hemoptysis. Chest CT shows a 3 cm cavitary lung lesion with a surrounding halo of ground-glass opacity. Serum galactomannan is positive. Which organism is most likely?
Show answer and explanation
Answer: A. Aspergillus fumigatus. Invasive pulmonary aspergillosis classically occurs in prolonged neutropenia with cavitary nodules, the halo sign on CT, and detectable serum galactomannan from septate fungal cell wall.
Why the other choices are tempting
- B. Rhizopus oryzae causes rhino-orbital-cerebral mucormycosis in diabetic ketoacidosis and broad non-septate hyphae with right-angle branching, not the halo-sign cavitary nodule with positive galactomannan.
- C. Pneumocystis jirovecii causes diffuse bilateral ground-glass interstitial pneumonia with elevated LDH in advanced HIV or steroid-treated hosts, not a single cavitary lesion.
- D. Cryptococcus neoformans causes meningitis and pulmonary nodules in HIV but does not produce the halo sign or galactomannan positivity.
- E. Nocardia asteroides causes pulmonary disease with branching filamentous gram-positive partially acid-fast bacilli in chronic steroid users, not septate fungal hyphae with galactomannan.
Flashcards
Tap a card to flip it.
What hyphae support Aspergillus?
Septate hyphae with acute-angle branching support Aspergillus.
What cavity complication supports Aspergillus?
A fungus ball in a preexisting lung cavity supports aspergilloma.
Quick answers
What is the fastest way to tell Aspergillus from Mucorales?
Aspergillus is septate acute-angle hyphae and cavity/neutropenia disease; Mucor is broad right-angle hyphae with DKA and necrotic eschar.
What is the key clue for Aspergillus?
Aspergillus causes allergic bronchopulmonary disease, fungus balls in cavities, or invasive pneumonia in neutropenia with septate acute-angle branching hyphae.
What is the key clue for Mucorales?
Mucorales cause rapidly invasive rhino-orbital-cerebral or pulmonary disease in diabetic ketoacidosis, neutropenia, or iron overload with broad right-angle hyphae.
What is the common trap with Aspergillus vs Mucorales?
Both can be angioinvasive molds, so hyphal morphology and host risk carry the answer.