"Hood Sign" in Nuclear Medicine: An Unusual Presentation of Mantle Cell Lymphoma as Detected on FDG PET/CT.

Mantle cell lymphoma is a rare and aggressive non-Hodgkin lymphoma with a high propensity for extranodal involvement, typically seen in the liver, marrow, and gastrointestinal system. Being an FDG-avid disease and a sensitive modality for detecting both nodal and extranodal disease, FDG PET/CT is recommended in the workup of mantle cell lymphoma. We present a rare pattern of cutaneous involvement of the head-neck region in a patient with mantle cell lymphoma, which can be described on FDG PET/CT as a "hood sign."