Extramedullary plasmacytoma (amyloid tumour) of the caruncle.

An 81-year-old man presented with a globoid caruncular mass of recent onset involving the left medial canthus. Pathological examination of the mass after its complete excision showed a roughly spherical subepithelial tissue deposit of amyloid, surrounded and sparsely infiltrated by plasma cells. The amyloid showed permanganate-resistant congophilia consistent with immunamyloid, and since most of the plasma cells stained positive for lambda light chains on immunohistochemical cytoplasmic staining, with no demonstrable heavy chains, the lesion was regarded as an extramedullary amyloid-producing plasmacytoma. Its solitary appearance in our patient, who has remained disease free, probably predicts the favourable prognosis generally associated with such lesions.