Exclusive lymphatic drainage from a melanoma on the back to intraabdominal lymph nodes.

Preoperative lymphoscintigraphy with Tc-99m antimony sulphide colloid was performed for a patient with a cutaneous melanoma on the left back. There was direct lymphatic drainage to retroperitoneal and paravertebral nodes but no drainage whatsoever to the axillary, inguinal, or triangular intermuscular space node fields, which would normally be expected to drain this area of the skin. Any attempt at sentinel lymph node biopsy in the axilla, groin, or triangular intermuscular space would have failed in this patient.