La linfogammagrafía en el estudio de los patrones de drenaje linfático en los pacientes con melanoma

BACKGROUND: In order to plan the pertinent surgical technique for each patient with melanoma or other skin malignancies, it is mandatory to identify those lymphatic basins at risk for metastases. The advent of radiotracers for functional studies of the cutaneous lymphatic system during the last decade has resulted in the disclosure of an unexpected interindividual variability of the lymphatic drainage in both head and neck and trunk. OBJECTIVE: To ascertain the usefulness of lymphoscintigraphy for depicting the cutaneous lymphatic draining basins in patients with primary melanoma of the head, trunk and limbs, and to compare the observed lymphatic drain with the expected pattern of lymph flow according to the classical anatomical studies. MATERIAL AND METHODS: Prospective study in a university hospital (Barcelones Nord area). Consecutive patients with the diagnosis of cutaneous melanoma were recruited after excisional biopsy of the primary tumor. Every patient was intradermally injected with rhenium-sulfide colloids or colloidal technetium labelled with Tc-99m in four quadrant doses of 0.3 ml around the lesions or its excisional scar. Scintigraphic imaging of the migrating radiotracer resulted in a flow pattern that was compared with its "classical" expected counterpart. RESULTS: Altogether, 55 lesions were studied, including 9 in the head, 21 in the trunk and 25 in the limbs (7 upper and 18 lower). The scintigraphic drain pattern did not match the expected classical pattern in 37.0% of the lesions overall (14% upper limbs, 42% truncal lesions out from an area 2.5 cm at both sides of Sapey's line or the midline, 16.6% lower limbs and 89% head and neck). CONCLUSIONS: Lymphatic drain of the skin shows a very high intrapersonal variability leading to the need for an individual work-up in order to know the lymphatic basins at risk for metastases. The high rate of unexpected or non-matching patterns casts some doubts over those previous studies that did not include lymphoscintigraphy on a patient-basis.