Adenoma of the non-pigmented epithelium of the ciliary body with smooth muscle differentiation: a unique case report

Adenoma of the non-pigmented epithelium of the ciliary body (ANPCE) is a relatively uncommon lesion usually presenting in the non-pigmented epithelium of the ciliary body, which belongs to the neuroectodermal origin. Histologically, this tumor consisted of sheets, cords, and tubules occasionally forming glandular configurations. The cells of the tumor had abundant eosinophilic cytoplasm with round nuclei and moderately prominent nucleoli, and separated by septa of extracellular matrix material. Herein, we present a case of adenoma of the non-pigmented epithelium of the ciliary body in a 48 year-old Chinese male. The tumor was clinically diagnosed as an amelanotic melanoma. Histologically, the tumor was predominately composed of sheets, strips, and tubular components, the tumor cells were round or spindle shaped, with round nuclei and an abundant cytoplasm where no pigment existed. Tumor cell nests were surrounded by hyalinized stroma, showing positive immunostaining for Actin of smooth muscle Actin (SMA) in the tumor and negative staining for S-100. As the most common primary neoplasms in the ciliary body were amelanotic malignant melanomas and metastatic carcinomas, the correct diagnosis of ANPCE may be a hard work.