Squamous cell carcinoma of the pectoralis major myocutaneous flap donor site.

The pectoralis major myocutaneous flap is considered a workhorse flap in the reconstruction of head and neck defects after cancer ablative surgeries and remains one of the most widely used reconstructive options. Complications at the donor site after the use of this flap, although rare, do occur and are usually restricted to minor infections, hematoma, and seroma formation. Metastasis to the flap donor site is a rare complication with limited documentation. Metastasis at the donor site usually follows local recurrence at the primary site, supporting the probable hypothesis of re-establishment of lymphatic drainage to the primary site by the flap pedicle. Tumor implantation, although a probable cause for metastasis at the donor site, cannot be confidently distinguished from other mechanisms, such as hematogenous spread or lymphogenous metastasis. This report describes a case that supports a seeding or tumor implantation mechanism of metastasis exclusively.