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.