Balloon cell nevi of the conjunctiva: Clinicopathologic correlation and literature review.

Balloon cell nevi are rare, benign melanocytic tumors that may involve the conjunctiva, choroid, and skin. In the ocular adnexa they typically present as raised and mobile hyperpigmented masses. Histologically, balloon cell nevi consist of large cells forming nests that usually lack melanin pigment. The balloon cells have a clear or vacuolated cytoplasm with centrally located nuclei. The vacuolated cytoplasm may be the result of defective melanin synthesis, with the accumulation of melanin precursors in premelanosomes. Balloon cells can resemble xanthoma cells, adipocytes, macrophages, sebaceous adenomas, melanoma with balloon cell changes, and metastatic renal cell carcinoma. Differentiating between these various entities via morphology and immunohistochemistry thus remains clinically significant. We report three cases of conjunctival balloon cell nevi and review the literature.