An unexpected, invasive disease of the mastoid bone and external auditory canal

A 65-year-old male patient with a history of Myelodysplastic Syndrome (MDS) and Systemic Mastocytosis (SM) presented with an invasive disease of the external auditory canal (EAC) and a parotid gland abscess. Abscess drainage and treatment for a malignant otitis externa (MOE) was started, which did not lead to clinical improvement. Computed Tomography (CT) of the petrous bone as well as a Positron Emission Tomography/Computed Tomography with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG-PET-CT) showed bony erosion of the EAC with a symmetrical FDG distribution at the level of both EACs. Histopathological biopsies of the EAC revealed a rarely encountered localization of systemic mastocytosis (SM). Especially patients with a hematological disorder such as a MDS are at risk to develop SM. In case of a fulminant infectious disease of the EAC in these patients, a localization of SM should be considered as well. This is the first report on SM with a localization in the EAC