Porokeratotic Eccrine Ostial and Dermal Duct Nevus

PEODDN is a rare benign cutaneous disorder that clinically resembles comedo nevus but favors the palms and soles, where pilosebaceous follicles are absent. Widespread involvement along Blaschko’s lines can also occur. It is a disorder of keratinization involving the intraepidermal eccrine duct (acrosyringium) and is characterized by eccrine hamartoma and cornoid lamellation in pathology. The patient is a 29-year-old man with an 8-year history of pruritic skin lesions on his right lateral ankle. In the pathologic examination, multiple small epidermal invagination with overlying parakeratotic cornoid lamellation, loss of granular layer, and few dyskeratotic cells at the base of epidermal invagination are revealed. After clinic-pathologic correlation, the diagnosis of porokeratotic eccrine ostial and dermal duct nevus (PEODDN) was made. Late-onset and rare clinical presentation as pruritic lesion are the characteristic features that make this patient an extraordinary presentation of PEODDN. 1. Introduction The term Porokeratotic Eccrine Ostial and Dermal Duct Nevus (PEODDN) was first described in 1980 by Abell and Read [1]. However, it was first described by Marsden et al. in 1979 [2]. PEODDN is a very rare skin condition which is classified as porokeratotic dermatoses. It is characterized by cornoid lamella which is a column of parakeratotic cells and is associated with dyskeratosis in the spinous layer as well as reduction in the number of granular zone cells. It is in close association with subjacent acrosyringia [3]. Here, we report a case with this rare condition. 2. Case Report A 29-year-old Iranian gentleman was referred to the Dermatology Department of RAZI Skin Hospital with severe pruritic skin lesions on his right lateral ankle that had presented since 8 years ago. Physical examination revealed multiple keratotic papules of similar size in a linear distribution forming verrucous plaques over the lower part of his right lateral ankle (Figure 1). Figure 1: Linearly distributed multiple keratotic papules of a similar size on the lower part of the right lateral ankle. He had no personal history of extracutaneous disease and no family history of similar lesions. One of the papules was removed by punch biopsy and examined under the microscope. Pathologic evaluation revealed multiple small epidermal invagination with overlying parakeratotic cornoid lamellation and underlying, slightly tortuous, eccrine duct nearby the epidermis. Loss of granular layer and few dyskeratotic cells were evident at the base of epidermal invagination (Figure 2). Figure 2: