Sentinel Node Mapping in Melanoma of the Back: SPECT/CT Helps Discriminate "True" and "False" in-Transit Lymph Nodes.

A 32-year-old man with melanoma on the right paramedian region of the lower back underwent lymphoscintigraphy for radioguided sentinel node (SN) biopsy. Planar imaging showed the presence of 2 sites of radioactivity accumulation corresponding to an axillary SN and to an "in-transit" SN, located on the right side of the upper trunk. A further "hot spot" placed on the left paramedian region of the lower back was identified by planar lymphoscintigraphy. This last finding could be mistaken for another "in-transit" SN, but SPECT/CT demonstrated it was actually a nonspecific radiopharmaceutical accumulation at the level of the right renal pelvis.