Study finds few eyelid basal cell carcinomas are pigmented

This retrospective observational case series evaluated the incidence and clinical and microscopic features of pigmented basal cell carcinomas (pBCC) of the eyelid. It found that while the incidence of pigmentation was low, the virtually universal presence of numerous latent and irregularly dispersed benign dendritic melanocytes in their invasive units gives all BCCs the potential to be pigmented.

Researchers reviewed microscopically all cases of BCC on file in their laboratory collected over a three-year period and correlated histopathologic findings with the clinical presence or absence of pigmentation. They then compared the results with those published for pBCC in the ophthalmic and dermatologic literature.

Only six of the 257 excised eyelid BCCs (2.3 percent) had clinically apparent pigmentation, either focal or diffuse, while another seven (2.7 percent) had histopathologically detectable but clinically insignificant pigmentation. The 2.3 percent prevalence is lower than what has previously been described in eyelids (median of 7.4 percent, with a range of 1 to 45 percent). This could be due to the putative ethnic or regional differences inherent in all series, or that the inclusion criteria for this study were microscopically stringent. Notably, all of the patients with clinically pigmented BCCs in this study were white.

Eight of the 13 lesions developed on the lower eyelids. All stained positively for melanin but negatively for iron. Microphthalmia-associated transcription factor (MiTF) highlighted numerous melanocytic nuclei in the tumor lobules, while MART-1 and HMB-45 revealed the dendritic shapes of the entrapped melanocytes. There was no difference in biological behavior between pigmented and nonpigmented BCCs.