Abstract
Abstract: :
Purpose: It is a frequent clinical observation that conjunctival melanocytic lesions show a tendency to increase in size during adolescence and pregnancy, and it has been speculated that this effect is due to an altered hormone status. We therefore aimed to evaluate the expression of sex hormone receptors and cell cycle proteins in melanocytic lesions of the conjunctiva. Methods: Formalin–fixed, paraffin–embedded material from 76 tumors – 69 conjunctival nevi (junctional [n=18], compound [n=32], dermal [n=18], and blue [n=1], 5 specimens of primary acquired melanosis (PAM), and 2 conjunctival melanomas – were included in a tissue microarray (TMA) format. The TMA sections were analyzed by immunohistochemistry with antibodies for progesterone and estrogen receptors, and cell cycle related proteins (p53, p16, MIB1–Ki67). Results: Progesterone receptors were highly (96%) and similarly expressed in all lesions. In addition, progesterone receptor expression showed a tendency to increase with age (p=0.06). In contrast, estrogen receptor expression was completely absent in all tumors. The cell cycle regulator p16 was expressed in 97%, p53 in 34% of the lesions. The proliferation marker MIB1–Ki67 was expressed at low levels (13 ± 14 SD %) in 79% of the lesions. No differences of expression were found between the different lesions and nevi types. The mean age of the patients was highest in conjunctival melanoma (70 ± 22 SD y), followed by PAM (60 ± 19 SD y) and nevi (36 ± 18 SD y). The different types of nevi did also show a significant age–dependency (junctional [25 ± 17 SD y] < compound [34 ± 17 SD y] < dermal [49 ± 15 SD y]). Conclusions: Our findings suggest a role for progesterone, p16, p53, and MIB1–Ki67, but not for estrogen, in the pathophysiology of melanocytic lesions of the ocular conjunctiva.
Keywords: conjunctiva • melanocytes • immunohistochemistry