View Case

Back

Questions
Discussion
References

Show the short figure legend

Show the complete figure description

1033) A renal transplant recipient developed an enlarging cavitating pulmonary lesion that did not respond to conventional antibiotic therapy. A tuberculin skin test was negative. A bronchoscopic biopsy was nondiagnostic. A lobectomy was performed. A section of the necrotic tissue surrounding the cavity was stained with Gomori methenamine silver (GMS) and disclosed fungal hyphae. All of the following statements about the infection are true EXCEPT:

Blood vessel invasion is a characteristic feature. Infarction leads to cavitation. The fungus belongs to the class of Zygomycetes that includes Rhizopus and Mucor. Risk factors include immunosuppression, neutropenia, hematologic malignancies, and uncontrolled diabetes mellitus. The lung is the most commonly affected organ.

Show Diagnosis/Topic

• Mucor is a broad, ribbonlike, pleomorphic hypha, branching at angles of between 45 and 90 degrees, with few or no septa (pauciseptate rather than aseptate).

• Most patients who develop this infection have an underlying disease; diabetes is the most common (36%).

• The most common clinical presentation in patients with diabetes is rhinocerebral mucormycosis (66%). In this population, pulmonary disease accounts for 16% of cases of mucormycosis.

• The inflammatory response may be neutrophilic (50%), predominantly granulomatous (5%), pyogranulomatous (25%), or absent (20%).

• Blood vessel invasion is said to be present in 100% of cases, and perineural invasion is present in 90%.

Frater JL, Hall GS, Procop GW: Histologic features of zygomycosis: emphasis on perineural invasion and fungal morphology. Arch Pathol Lab Med 2001;125(3):375-378.

Sun HY, Singh N: Mucormycosis: its contemporary face and management strategies. Lancet Infect Dis 2011;11(4):301-311.

Back

Anatomic Pathology: Infectious Disease Pathology

View Notes

Add a Note