Extraordinary Lymph Drainage in Cutaneous Malignant Melanoma and the Value of Hybrid Imaging: A Case Report.

In melanoma patients, preoperative lymphoscintigraphy has become a gold standard. The role of single-photon emission computed tomography (SPECT) or its combination with computed tomography (SPECT-CT) as part of the standard sentinel scintigraphy protocol has yet to be determined. A 46-year-old female patient with melanoma of the trunk received preoperative lymphoscintigraphy and subsequent surgical excision. Planar imaging displayed two hot spots in the region of the primary lesion. No other lymphatic flow pathways could be appreciated. Two focal hot spots, one dorsal to the primary lesion near the left latissimus dorsi muscle and one just lateral to the primary lesion in the subcutaneous tissue, were appreciated with SPECT-CT imaging. The primary melanoma lesion, as well as the two additional lesions, which were detected by SPECT-CT, were excised and sent for histopathological examination. While the primary lesion was a superficial spreading melanoma, the lesions appreciated in SPECT-CT revealed four sentinel lymph nodes, each of which was negative for tumor cells. Melanomas, especially of the trunk, can demonstrate multiple lymphatic drain basins in a large percentage of patients. Given that without the detailed anatomical information provided by SPECT-CT it would be very difficult to locate the diverse lymphatic drain basins and their lymph nodes, we would suggest routinely implementing SPECT-CT in the standard planar sentinel imaging protocol.