Concomitant Neck and Lung Masses Post Dental Procedure—A Potential Novel Presentation of the Cellulosimicrobium Species in Humans

<b>Background:</b> <i>Cellulosimicrobium</i>, formerly known as the <i>Oerskovia</i> genus, is a Gram-positive organism known for its characteristic bright yellow colonies. While abundant in nature, it is very rarely linked to pathogenesis in humans. While there is no classical presentation for <i>Cellulosimicrobium</i>-associated infections, cases tend to be foreign body-related or involve immunocompromised patients. Rates of <i>Cellulosimicrobium</i>-associated infections have been hypothesised to rise in the future, due to rising numbers of immunocompromised patients in the community and increasing usage of foreign bodies such as prostheses and long-term catheters. Existing technical difficulties regarding misidentifying cultures as other species (often other coryneforms) may also play a significant role in the low number of documented cases, and this may change in the near future with diagnostic advancements such as whole genomic sequencing. <b>Case Presentation:</b> A 57-year-old immunocompetent Irish male presented with concomitant neck and lung masses. Notably, this was found to be directly following a recent dental procedure. During extensive investigations, <i>Cellulosimicrobium</i> was isolated from biopsied lung tissue using 16S ribosomal ribonucleic acid gene-sequencing analysis. The patient was treated with long-term oral amoxicillin and safely discharged, with both masses showing measurable reductions in size on subsequent imaging. <b>Conclusions:</b> Should <i>Cellulosimicrobium</i> represent the causative pathological organism in this case, then we believe this to represent a potential novel documented presentation of the organism's pathogenesis in humans. We provide detailed discussion surrounding the successful management of this patient and the evaluation of the evolving differential diagnosis throughout this case.