Topical mitomycin chemotherapy for conjunctival malignant melanoma and primary acquired melanosis with atypia: Clinical experience with histopathologic observations

Objectives: To clinically evaluate topical mitomycin chemotherapy in patients with diffuse, multifocal, or recurrent primary acquired melanosis with atypia and/or conjunctival malignant melanoma and to histopathologically study ocular tissue samples obtained before and after treatment. Methods: Chemotherapy with topical mitomycin, 0.04% 4 times daily, was administered for 28 days as the primary and only treatment in 7 patients (after biopsy) and for 7 days as adjuvant therapy to excision and cryotherapy in 5 patients. Mean follow-up was 38 months. Five patients developed subconjunctival recurrences, for which 2 underwent orbital exenteration and 3 were treated conservatively. Histopathologic specimens of conjunctival, adnexal, and ocular tissues obtained before and after chemotherapy were evaluated. Results: Regression of tumor was observed in 11 patients with primary or adjuvant topical mitomycin chemotherapy. One patient with nodular melanoma was resistant to mitomycin chemotherapy. Histopathologic findings included regionally variable conjunctival epithelial atrophy and thinning. Dyskeratosis and focal keratinization in conjunctival epithelium were noted. Epithelial nuclei were occasionally pyknotic in areas of atrophic epithelium. Subepithelial inflammation was present and was most intense in areas with severe atrophy and/or keratosis. Two patients with primary treatment and 2 with adjuvant treatment developed subconjunctival recurrence. In patients with recurrent malignant melanoma, the deeper layers of the lamina propria were involved, with sparing of the epithelium and superficial lamina propria. Transient keratoconjunctivitis was observed in all patients during treatment. In evaluation of the exenteration specimens, corneal, scleral, episcleral, retinal, and anterior structures were within-normal limits. Conclusions: Topical mitomycin chemotherapy was found to induce regression of conjunctival melanoma and primary acquired melanosis with atypia. When mitomycin chemotherapy was used as an adjuvant to excision and cryotherapy, 2 (40%) of 5 patients experienced tumor recurrence at a mean of 4.3 years' follow-up. Our histopathologic findings demonstrated a long-term mitomycin chemotherapy- related effect on the conjunctiva. The degree of chronic atrophy and inflammation was not clinically significant. The pattern of effect and location of recurrent disease suggest that this regimen of topical mitomycin chemotherapy was most effective for superficial tumors. No complications that would preclude use of our dose regimen were noted. Although subconjunctival or orbital recurrences were noted, topical mitomycin chemotherapy warrants further investigation as an alternative treatment for primary acquired melanosis with atypia and conjunctival malignant melanoma.