Is this psoriasis or something else?

A 38-year-old man presented with a history of intractable itchy eruption on the buttocks, present for the last 6 years. The lesions had gradually spread over time and did not respond to several topical steroids. Dermatological examination revealed a butterfly-shaped erythematous verrucous plaque, involving both buttocks and gluteal cleft [Figure 1], and peripheral guttate red-brown discrete papules [Figure 2]. Histologic examination of a punch biopsy specimen displayed orthokeratosis, follicular plugging, numerous oblique columns of parakeratosis called cornoid lamellae, extending at about 45 degrees from the surface of