Recurrent head and neck desmoplastic melanoma with perineural spread along the nervus mandibularis revealed by 18F-FDG PET/CT.

This report describes a rare case of recurrent head and neck desmoplastic neurotropic melanoma with perineural spread along the nervus mandibularis. An 87-year-old male presented with a rapidly growing mass on the right side of the chin, 4 years after surgical excision of a desmoplastic non-melanotic melanoma of the tip of the chin, with lymphadenectomy of the right side submental and submandibular areas. A panoramic X-ray showed extensive widening of the mandibular canal compatible with perineural tumour growth. (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) images revealed intense pathological uptake in the recurrent tumour mass located in the right lower buccal fold, and linear pathological uptake in the mandibular canal. Although magnetic resonance imaging is considered the standard of reference, recognition of perineural spread on (18)F-FDG PET/CT is important, as it usually leads to a change in patient management from cure to palliation and may avert further diagnostic procedures.