Abstract

Rothia mucilaginosa, a gram-positive encapsulated organism and a commensal in the upper aerodigestive tract, can rarely cause opportunistic infections in immunocompromised patients, particularly in the setting of hematologic malignancies. Of the approximately 50 reported cases in the English literature, majority of which were bacteremia, only two were cutaneous R. mucilaginosa infections. Here, we report three additional cases and highlight the clinico-pathological features. The patients included 51-year-old (yo) woman with remote (3 years prior) history R. mucilaginosa bacteremia, 72-yo and 26-yo men with relapsed/refractory acute myeloid leukemia, presenting with neutropenic fever. Clinical presentation was new onset erythematous pink ill-defined 0.5-2.0 cm macules, patches and firm papules lacking vesiculation, warmth or fluctuance; older lesions showed mild scaling and crusting, with mild tenderness in one patient, but otherwise asymptomatic. Biopsies revealed intravascular dense clusters of numerous small spherical organisms with variably thick capsule, measuring ~1-1.5 mm without and ~3-4 mm including capsule, positive for Gram, PAS and GMS stains, and negative for Fite, mucicarmine and Fontana Masson stains, histomorphologically consistent with R. mucilaginosa. Concurrent blood cultures were positive for R. mucilaginosa only in the 72-yo man, while all recent and concurrent blood and tissue cultures failed to grow R. mucilaginosa in the other two patients. While the 26-yo man is currently alive, the 52-yo woman and 72-yo man died 8 months and 1 week, respectively after the appearance of skin lesions. The predominantly negative culture results in our cases highlight the need for histomorphologic identification of R. mucilaginosa for appropriate patient management.