Hypoepiluminescence Microscopy of Pigmented Skin Lesions: New Approach to Improve Recognition of Dermoscopic Structures

BACKGROUND: Hypoepiluminescence microscopy (HELM) is a new dermoscopic approach for analysis of pigmented skin lesions (PSLs) after surgical excision. OBJECTIVES: The objective was to verify whether this method could provide additional morphologic information for diagnostic or didactic purposes compared to conventional epiluminescence microscopy (ELM). PATIENTS AND METHODS: Thirty-one PSLs from 30 patients were consecutively evaluated by ELM and, after excision, by HELM. For HELM examination, the lesion was positioned on a glass slide and illuminated from above with a halogen lamp and from underneath with an LED source. All lesions were subsequently examined histopathologically. RESULTS: In 11 of 31 (35.5%) lesions, a typical pigment network, as assessed by ELM, appeared bidimensional with HELM. In 9 lesions (9/31; 29%) ELM showed a gray-blue area, while HELM allowed us to distinguish 5 lesions (5/9, 55.5%) with gray area predominant showing a lichenoid lymphocytic infiltration and few melanophages from the other 4 lesions (4/9, 44,5%) with heavy dermal accumulation of pigmented melanocytes or melanophages where a blue area was clearly visible at HELM. In 9 other cases (29%), ELM analysis revealed a central homogeneous dark brown/black pigmentation that in 7 cases was seen under HELM examination to consist of globules. CONCLUSIONS: HELM is particularly useful in evaluating heavily PSLs or structures located in the reticular dermis.