Wedge resection of a solitary lung mass
Clinical history
A 66-year-old woman presented with a solitary lung mass. Imaging characteristics were suggestive of malignancy. A wedge resection of lung was performed.
Pathological Findings
Gross examination of the wedge resection specimen showed a three-centimeter well-circumscribed, grey-white friable mass with central necrosis. The mass was sampled for frozen and permanent sections.
Low-power H&E of the mass.
Medium-power H&E of the mass.
Microscopic examination revealed that the mass was composed of a tangled network of septate hyphal elements. The inflammatory reaction in the surrounding tissue was sparse. Closer inspection revealed distinct acute angle hyphal branching, and occasional well-formed fruiting heads were seen.
A high-power view showing branching hyphae and two brown-pigmented conidia.
A single row of phialides cover the surface of the round vesicle (center).
Diagnosis
Mycetoma, favor Aspergillus species.
Discussion
Aspergillosis is a ubiquitous fungal organism which can sometimes be found in the sputum of healthy people. Depending on a variety of factors (like host immune status, for example) the organism can cause any of three main clinical syndromes: allergic pulmonary aspergillosis, invasive aspergillosis, and mycetoma (as seen in this case). The morphology in this case is consistent with Aspergillus species, but further categorization is probably best left to culture.
Mycetoma usually occurs in an immunocompetent host via colonization of a pre-existing cavitary lung lesion, particularly those related to tuberculosis. Fungal organisms proliferate to fill the cavity, forming a mass. There is sometimes a significant host inflammatory response, and necrotic fungal organisms and debris may be present. Patients with mycetomas sometimes present with hemoptysis or productive cough, but many remain asymptomatic and their lesions are discovered incidentally. If the host becomes immunosupressed (especially neutropenic) the infection can become invasive.
References:
1. DoctorFungus.org
2. Kumar V, Abbas A, Fausto N. Robbins and Cotran Pathologic Basis of Disease, 7th ed. 2007. Elsevier.
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