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Editor,—Although the presence of melanocytes located within and under the epithelium of the nasal cavity and paranasal sinuses has been reported, it appears to be a rare finding.1 Further, only 17 cases of malignant melanoma of the lacrimal sac have been reported.2 We came across unusual, and unaccounted for, focal collections of melanocytes in the lacrimal sac of a patient and report this finding.
A 55 year old woman presented to the ophthalmology department of the Schieffelin Leprosy Research and Training Centre with a left sided lacrimal mucocele. Since she also had a cataract that needed surgery, a dacryocystectomy was done in January 1999. During surgery, when the lacrimal sac was being dissected, a localised small area of black pigmentation was seen on the sac. The excised sac was sent for histopathological examination to rule out melanoma. There were no associated pigmentations on the skin overlying the sac or any fistulas in the region.
Histopathological examination of the lacrimal sac showed focal and diffuse collections of cells containing blackish-brown pigments in the stroma and the epithelial cells of the sac. Inflammatory cell collections consisting of lymphocytes, histiocytes, and plasma cells were also seen in the stroma (Fig 1). The intracellular pigment gave negative results when stained with Perl's stain for haemosiderin3 but gave a positive result when stained with Fontana-Masson stain for melanin (Fig 2).4 The pigment was completely bleached and removed,5 thus confirming that the pigment present was melanin.
The pigmentation in the lacrimal sac was a chance finding. The cells containing the pigment were confirmed to be melanocytes by the Fontana-Masson staining. The origin of malignant melanoma of the sac is uncertain.2 Presumably, it can arise from nests of melanocytes located either within the epithelium of the lacrimal sac or in the underlying stroma.2 This histopathological finding establishes that melanocytes can be found in isolation in the lacrimal sac. A morphologically similar histopathology can be seen in blue naevus and in the naevus of Ota but clinically the patient did not exhibit any ocular melanosis nor was the skin of the face pigmented.