case_images: PMC11233541_01
case_images: (A,B) The patient's lesions presented as flat reddish macules and papules on the abdomen (A) and trunk (B). (C,D) The patient presented with multiple well-circumscribed keratotic papules bilaterally distributed on the lower extremities.
case_images: fmed-11-1415545-g001.jpg
case_images: PMC11233541_01_fmed-11-1415545-g001.jpg
case_images: fig1
case_images: The patient reported subsequent spread of the lesions to his trunk and abdomen (Figure 1). On physical examination, crateriform lesions with an erythematous base and crusty substance inside (Figures 1C,D), along with similar but smaller lesions on his trunk and abdomen (Figures 1A,B). The findings were consistent with reactive perforating collagenosis, as evidenced by the presence of collagen elimination before (Supplementary Figures 1A,B) and after complete penetration through the epidermis (Figures 2A,B; Supplementary Figures 1C,D).
case_images: Histopathological examination of the biopsy specimen. (A) A skin biopsy sample from the papule located on the lower extremity demonstrated degenerated collagen bundles that had been eliminated to form a cup-shaped epidermal depression (HE, x10, arrow). (B) High-power view highlighted the degenerating collagen bundles, vertically oriented, and the basophilic debris within the crater. Numerous neutrophils and lymphocytic infiltration were seen directly under the depression (HE, x100, arrow). (C) Collagen bundles perforated the base of the epidermal erosion (Masson's trichrome staining, x10, arrow). (D) High-power view highlighted the degenerating collagen bundles, vertically oriented, and the basophilic debris within the crater (Masson's trichrome staining, x100, arrows).
case_images: fmed-11-1415545-g002.jpg
case_images: PMC11233541_01_fmed-11-1415545-g002.jpg
case_images: fig2
case_images: Histopathological examination revealed degenerated collagen bundles that had been eliminated to form a cup-shaped epidermal depression (Figure 2A). Numerous neutrophils and lymphocytic infiltration were seen directly under the depression (Figure 2B). The findings were consistent with reactive perforating collagenosis, as evidenced by the presence of collagen elimination before (Supplementary Figures 1A,B) and after complete penetration through the epidermis (Figures 2A,B; Supplementary Figures 1C,D). Masson's trichrome staining showed that collagen bundles perforate the base of the epidermal erosion (Figure 2C). High-power view highlighted the degenerating collagen bundles, vertically oriented, and the basophilic debris within the crater (Figure 2D).