Anatomy and Embryology of the Eyelids: A Review with Special Reference to the Development of Divided Nevi

Abstract

In this review of the basic anatomy and embryology of the human eyelids, the sequence of eyelid differentiation is discussed. The development is important in exploring the formation of divided or "kissing" nevi of the lids. Since the lids are fused from the ninth week until the twentieth week of gestation, one may propose that the precursor elements of the nevus develop during that specific time. Because the epithelium only is fused, melanocytes derived from the neural crest must begin their differentiation in the region of the fused epithelium.

Congenital melanocytic nevi: Clinical and histopathologic features, risk of melanoma, and clinical management

“…This finding implies that congenital melanocytic nevi develop between the 9th and 20th week of gestation, when the eyelids are fused. 15 …”

Kissing Nevus of the Penis

“…Since the first case report by Von Micheal in 1908, a few kissing nevi have been reported located on the upper and the lower eyelids1-3. A kissing nevus appears to be a single lesion when the lids are closed.…”

Divided naevus of the penis: two paediatric cases with dermoscopic findings

“…Divided or kissing naevi are located on adjacent parts of the body that are separated during embryogenesis . Such lesions were first described by Von Michael in 1908, and named by Fuchs in 1919, describing a congenital melanocytic naevus that occurred on adjacent parts of the upper and lower eyelids, and appeared to be a single lesion when the eye was closed . Other types of divided naevi have been reported less frequently, and include naevus spilus on the eyelids, and an epidermal naevus on the fingers .…”