[463] Lymphatic Invasion in Melanocytic Tumors of Uncertain Malignant Potential May Predict Worse Outcomes.

Ronnie M Abraham, David E Elder, Lorenzo Cerroni, Martin Mihm, Xiaowei Xu. University of Pennsylvania, Philadelphia; Medical University of Graz, Austria; Harvard Medical School, Boston, MA

Background: Melanocytic tumors of uncertain malignant potential (MELTUMPs) are a subset of difficult melanocytic lesions that evade consensus from novice and expert alike. These lesions are bulky dermal melanocytic tumors that include atypical forms of spitzoid, cellular blue, and deep penetrating nevi, with features of both benign nevi and malignant melanoma. Previous studies of these lesions have shown that patients generally have favorable outcomes, with features such as mitotic activity, mitotic activity near the base, and inflammatory infiltration of the tumor as characteristics that may predict a more aggressive course. Lymphatic invasion has been found to a potential predictor of regionally metastatic disease in malignant melanoma. We attempt to test whether lymphatic invasion in MELTUMPs may be indicative of a worse prognosis.
Design: Fifty-five melanocytic lesions diagnosed as MELTUMPs at our institution and elsewhere were procured. Dual immunohistochemical staining for D240 and S100 is performed on the unstained tissue sections. Clinical follow up has been obtained for some of the patients.
Results: Of the thirty four cases of MELTUMPs currently stained, lymphatic invasion was found in 6 of them (6/34, 17.6%). Clinical history is currently obtained for 12 patients, with the current average clinical follow up being 10.9 years. Of these 12, four patients have clinical evidence of having a malignant course, and two of these patients have lymphatic invasion by dual immunohistochemistry (2/4, 50%).
Conclusions: Our preliminary data thus far shows that lymphatic invasion found by our method is quite promising as a potential tool to predict which MELTUMPs are more likely to develop a malignant course. Additional staining and clinical information gathering is currently ongoing to complete the study.
Category: Dermatopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 111, Tuesday Morning


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