Few studies have compared melanocyte densities in inhabitants of areas with different levels of solar exposure. These investigators analyzed the density of melanocytes in sun-exposed, nonlesional skin from patients (50 Florida residents and 50 Minnesota residents) who had undergone Mohs surgery for basal and squamous cell carcinomas. They examined melanocytic density, confluence, pagetoid spread, and growth along hair follicles in paraffin-fixed sections stained by hematoxylin-eosin (H&E) and Melan-A.
The two stains produced differing results: Mean melanocyte density per high-power field (HPF) was 9.3 with H&E and 12.0 with Melan-A. Melanocyte density was higher in Florida residents with H&E staining and in men with Melan-A staining; the number of melanocytes decreased with age in inhabitants of both states, particularly with Melan-A. Confluence was more common in Melan-A–stained sections (45%, vs. 24% with H&E). The researchers also examined these noncancerous specimens of sun-damaged skin for features characteristic of melanoma: Cytologic atypia appeared in 19%, follicular extension in 7%, pagetoid spread in 3%, and high confluence (3–8 melanocytes on the row) in 1%.
Comment: Often the pathologist needs to differentiate between increased densities of melanocytes in background solar-damaged skin and in the melanocytic lesion. This call is critical in lesions in sun-exposed, sensitive areas such as the head and neck, where melanocytes are more common than elsewhere on the body. Confluence, pagetoid spread, and growth along adnexal structures are also relevant for identifying melanocytic lesions. This study provides easy and reproducible rules for defining background (e.g., 9–14 melanocytes per HPF and growth along the hair <1 mm in depth). Comparison of skin at the periphery of large excisions in melanoma patients will be extremely valuable. A cautionary note for those who use Melan-A: Confluence can be misleadingly increased compared with basic H&E staining, especially in inflamed areas. Keeping this in mind will avoid overcalls.
The two stains produced differing results: Mean melanocyte density per high-power field (HPF) was 9.3 with H&E and 12.0 with Melan-A. Melanocyte density was higher in Florida residents with H&E staining and in men with Melan-A staining; the number of melanocytes decreased with age in inhabitants of both states, particularly with Melan-A. Confluence was more common in Melan-A–stained sections (45%, vs. 24% with H&E). The researchers also examined these noncancerous specimens of sun-damaged skin for features characteristic of melanoma: Cytologic atypia appeared in 19%, follicular extension in 7%, pagetoid spread in 3%, and high confluence (3–8 melanocytes on the row) in 1%.
Comment: Often the pathologist needs to differentiate between increased densities of melanocytes in background solar-damaged skin and in the melanocytic lesion. This call is critical in lesions in sun-exposed, sensitive areas such as the head and neck, where melanocytes are more common than elsewhere on the body. Confluence, pagetoid spread, and growth along adnexal structures are also relevant for identifying melanocytic lesions. This study provides easy and reproducible rules for defining background (e.g., 9–14 melanocytes per HPF and growth along the hair <1 mm in depth). Comparison of skin at the periphery of large excisions in melanoma patients will be extremely valuable. A cautionary note for those who use Melan-A: Confluence can be misleadingly increased compared with basic H&E staining, especially in inflamed areas. Keeping this in mind will avoid overcalls.
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