PMC10294214_01
a The red spot indicates the site of the punch biopsy. The image was taken in February 2017 at the time of initial presentation prior to any treatment. b Modest improvement in the skin lesion after 18 months of keratolytic topical treatment. The image was taken in October 2018.
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F1
The skin lesion was 4 x 3 cm in size, as shown in Figure 1a, b.
Microscopic appearance of the lesion. a H&E section showing intraepidermal cellular and stromal debris forming a plug and underlying degenerated keratinocytes. Trichrome and elastin histochemical stains shown in b and c, respectively, are negative for collagen and elastic fibers in the degenerated material.
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F2
Histopathological examination revealed a cup-shaped plug of parakeratosis with neutrophils and melanin pigment (Fig. 2).