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Pigmentation of the Lacrimal Sac Epithelium
Frederick A Jakobiec1, Anna M Stagner, Francis C Sutula
1* David G. Cogan Ophthalmic Pathology Laboratory, and † Ophthalmic Plastic Surgery Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, U.S.A.
Purpose:
To describe the patterns of the melanocytic populations of 3 cases of lacrimal sac benign melanosis and 1 of atypical primary-acquired sac melanosis with a melanomatous nodule secondary to spread of atypical conjunctival primary-acquired melanosis to the sac.
Methods:
Clinical records, photographs, and paraffin sections stained with hematoxylin and eosin and the Fontana reaction were critically reviewed. Additional sections were immunoreacted for melanoma antigen recognized by T cells and microphthalmia-associated transcription factor. Five nonpigmented pterygia and 4 nonpigmented lacrimal sacs served as controls.
Results:
Three patients with obstructive dacryocystitis and benign melanosis were African-Americans whose sacs disclosed the presence of nonclustering, melanoma antigen recognized by T cells, and microphthalmia-associated transcription factor-positive intraepithelial dendritic melanocytes at all levels of the epithelium. The transferred melanin granules were concentrated in the adlumenal apical region of the epithelial cells. No fusiform melanocytes were found in the lamina propria. The fourth patient, a white, had atypical conjunctival and sac primary-acquired melanosis and conjunctival and sac melanomas. The intraepithelial sac melanocytes in this case were strikingly atypical and profusely distributed in a back to back fashion at all levels of a thickened epithelial layer focally approximating the appearance of a melanoma in situ. Five nonpigmented pterygia and 4 nonpigmented lacrimal sacs served as controls. Each displayed nonnesting dendritic melanocytes of various densities without back to back contact.
Conclusion:
Low densities of intraepithelial melanocytes were discovered in all controls and therefore represent a normal subpopulation within the conjunctival and lacrimal sacs. Due to the pseudostratification of the sac epithelium, melanocytes can move to higher levels without implying atypia. Benign melanosis is produced by small diffusely distributed individual intraepithelial melanocytes, whereas primary-acquired melanosis with atypia exhibits back to back, dense proliferations of large atypical melanocytes.
