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PRAME immunohistochemistry as an adjunct for diagnosis and histological margin assessment in lentigo maligna
Author(s) -
Gradecki Sarah E,
ValdesRodriguez Rodrigo,
Wick Mark R,
Gru Alejandro A
Publication year - 2021
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.14312
Subject(s) - medicine , lentigo maligna , biopsy , immunohistochemistry , lentigo maligna melanoma , histopathology , pathology , surgical margin , melanoma , cancer , cancer research
Aims Lentigo maligna (LM), the most common type of melanoma in situ , is a diagnostically challenging lesion for pathologists due to abundant background melanocytic hyperplasia in sun‐damaged skin. Currently, no laboratory methods reliably distinguish benign from malignant melanocytes. However, preferentially expressed antigen in melanoma (PRAME) has shown promise in this regard, and could potentially be applied to diagnosis and margin assessment in difficult cases of LM. Methods and results Ninety‐six cases with a diagnosis of LM ( n = 77) or no residual LM ( n = 19) following initial biopsy were identified and stained with an antibody directed towards PRAME. Immunohistochemistry (IHC) was scored as positive or negative, and measurement of histological margins by PRAME was performed and compared to the measurement of histological margins using conventional methods [haematoxylin and eosin (H&E) and/or sex‐determining region Y‐box 10 (SOX10) and/or Melan‐A]. Of cases with LM, 93.5% (72 of 77) were PRAME + and 94.7% (18 of 19) of cases with no residual LM were PRAME – . Of the 35 cases with no margin involvement by PRAME or conventional assessment, 14 cases (40.0%) had no difference in measurement, 17 (48.6%) had a difference of 1 mm or less and four (11.4%) differed by between 1 and 3.5 mm. There was a high correlation between margin assessment methods ( r = 0.97, P < 0.0001). Conclusions PRAME IHC is a sensitive (93.5%) and specific (94.7%) method for diagnosing LM on biopsy and excision, and measurement of histological margins by PRAME shows a high correlation with conventional methods for margin assessment. Furthermore, the nuclear expression of PRAME makes it a good target for use in dual‐colour IHC stains.