Background: To assess the usefulness of routine melan-A immunohistochemistry (IHC) for exclusion of microinvasion in lentigo maligna (LM).
Methods: One hundred and twenty cases of LM from our archives were reviewed by 2 authors with S100 protein and melan-A IHC using a red chromogen.
Results: Melan-A was useful to confirm the diagnosis of LM in early lesions and to differentiate these from chronically sun-damaged skin. The presence of scattered melan-A–positive cells was noted in the dermis in 72 of 120 cases (melanophages in 36 cases, nonspecific cells different to melanophages in 16 cases, and a dual cell population in 20 cases). The significance of these cells was uncertain. Only 3 cases suspicious for microinvasion were identified: 2 on haematoxylin and eosin and 1 on S100.
Conclusions: We recommend use of melan-A to confirm the diagnosis in early lesions of LM and in the differential diagnosis from melanocytic hyperplasia in chronically sun-exposed skin. We do not recommend routine use of melan-A to identify or exclude microinvasion. However, it may have a role, in conjunction with S100, in cases with suspicious features for early invasion on haematoxylin and eosin sections.
*Department of Dermatology, Basildon University Hospital, Essex, United Kingdom; and
†Department of Dermatopathology, St John's Institute of Dermatology, St Thomas' Hospital, London, United Kingdom.
Reprints: Omair Akhtar Hameed, MBBS, BSc, MRCP, Department of Dermatology, Basildon University Hospital, Nethermayne, Basildon, Essex SS165NL, United Kingdom (e-mail: omair.hameed@btuh.nhs.uk).
The authors declare no conflicts of interest.
Presented at the Dermatopathology Special Interest Group at the BAD Annual Meeting on July 3, 2012; Brimingham, UK.
