Pagetoid dyskeratosis of hands: Report of two cases and the usefulness of dermoscopy

Dermoscopy showed a brown pigmentation with parallel ridge pattern sparing the furrows [Figure 1]b. A skin biopsy demonstrated some large keratinocytes in the upper layers of the epidermis, with pale cytoplasm and pyknotic nucleus, surrounded by a clear halo [Figure 1]c. A year later, she started working as a salesperson and the pigmentation almost completely disappeared [Figure 1]d.{Figure 1} Case 2 A 31-year-old woman presented with a 3-year history of brown spots on her fourth left finger [Figure 2]a, which progressively increased in size. A few months later, the discoloration had almost disappeared spontaneously [Figure 2]c.{Figure 2} Pagetoid dyskeratosis is thought to be a reactive keratinocyte response to mechanical trauma which leads to premature keratinization of a small part of the normal keratinocyte population. [5] The parallel ridge pattern is highly specific for acral melanoma [Figure 3]a. However, there are exceptions wherein benign lesions may show such a pattern, such as lentiginoses, congenital naevi, acral angioma, subcorneal hemorrhages [Figure 3]b, exogenous pigmentation [Figure 3]c, pigmented warts, blue naevi, chemotherapy-induced hyperpigmentation, postraumatic purpura due to repetitive microtrauma and rare cases of benign acral melanocytic nevus [the parallel furrow pattern is more frequent in acral naevi–[Figure 3]d.[5] Two cases of brownish pigmentation of finger[2] and palm,[3] respectively, have been reported, both showing a parallel ridge pattern on dermoscopy and pagetoid dyskeratosis on the skin biopsy.