Metastatic melanoma vs lymphoma. Using a sentinel lymph node biopsy a diagnostic tool.

Sentinel lymph node biopsy (SLNB) is a prognostic tool used in cases of melanoma with a stage IB or greater and the absence of clinical lymphadenopathy. A positive SLNB historically indicated a need for regional lymph node clearance. However, cases of clinical lymphadenopathy in the presence of primary melanoma negates the use of SLNB and rather the British Association of Dermatologists advocate a primary block dissection of regional lymphatic tissue [NICE UK. Melanoma: assessment and management. NICE Guideline NG 14. 2015]. The following describes the case of a patient with an original stage II melanoma and a concurrent diagnosis of B cell lymphoma associated with widespread lymphadenopathy. Our multi-disciplinary team believe the use of SLNB is a more informative investigation compared with ultrasonograpphy and fine needle aspiration for such cases. In cases of clinical uncertainty due to a dual diagnosis of lymphoma, cytology would not provide nodal morphology or histological architecture, required for lymphoma grade and subtype.