A rare case of thoracic actinomycosis presenting as a breast mass in a male patient, likely resulting from aspiration of oropharyngeal secretions.
Actinomycosis should be considered in male breast masses; this case extends known presentations but remains hypothesis-generating.
(See page 438 for the Photo Quiz.) Diagnosis: Actinomycosis caused by Actinomyces israelii. Actinomyces species are gram-positive, non-spore-forming, and predominantly anaerobic bacteria. They are commensals of the human oropharynx, gastrointestinal tract, and female genitalia [1]. Certain pathogenic species are unique to humans. Diagnosis is frequently delayed until biopsies are performed to evaluate for malignancies. Our patient had periodontal disease. It is likely that thoracic disease resulted from aspiration of oropharyngeal secretions. Figure 1 shows multiple sulfur granules. These comprise colonies of the organism. Figure 2 shows a higher magnification of one granule. It is unusual for so many granules to be seen on histology. A study of 181 cases found only one granule in 25% of lesions [2]. Based on this finding, the patient was started on penicillin (5 million units every 6 hours intravenously). However, when the breast fluid culture grew Actinobacillus actinomycetemcomitans, the original diagnosis was questioned.
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Tang et al. (2015) studied this question.
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