Cutaneous allergic reaction to subcutaneous vitamin K1: A case report and review of literature

Figure 1 Clinical presentation and diagnostic clues from the original symptoms. A and B: Intensely pruritic, weeping, erythematous, eczematous, and indurated plaques; C: An intense perivascular infiltrate composed of lymphocytes and histiocytic cells, with rare plasma cells and eosinophils (hematoxylin–eosin stain, 100 ×); D: Prominent endothelial cell swelling. The infiltrate extended through the reticular dermis into the subcutaneous fat and focally surrounded the eccrine and neural structures (hematoxylin–eosin stain, 400 ×); E and F: The lower half of the dermis was markedly sclerotic with thickened eosinophilic collagen bundles. A microscopic examination revealed a normal epidermis and more lymphocytes infiltrating the blood vessels in the dermis, several of which were mimicking Pautrier microabscesses (100 ×).

Figure 2 Immunohistochemical assay for positive phenotypes. A-D: T cells tested positive for CD3, CD5, and CD4 and partially positive for CD8 (200 ×); E and F: B cells tested positive for CD20 and CD79a (200 ×).

Figure 3 Immunohistochemical assays for other phenotypes. A-C: Histocytes were positive for CD68+, natural killer cells tested positive for CD56, and mastocytes tested negative for CD117 (200 ×).

Figure 4 Clinical presentation before and after treatment. A: Appearance of the skin before treatment (September 14, 2021); B: Appearance of the skin during follow-up (March 6, 2022). In the 1.5 years follow-up period, the area of erythema was reduced, the degree of itching was alleviated, and the patient’s condition gradually stabilized.

Figure 5 Case timeline. Important dates, times, and detailed diagnostic process during the treatment and follow-up period.