Nodular Scleroderma in a Patient With Anti-RNA Polymerase III-Antibody Positive Systemic Sclerosis: A Case Report and Literature Review.

Nodular scleroderma (NS) is a rare manifestation of systemic sclerosis (SSc) that can clinically resemble keloids, often leading to diagnostic difficulty. Herein we report a case of a 76-year-old woman with anti-RNA polymerase III antibody-positive SSc who developed progressive erythematous, pruritic, keloid-like plaques 3 months after rituximab therapy. Histopathology showed thickened collagen bundles extending from the superficial to mid-dermis, increased fibroblasts, mucin deposition, and reduced elastic fibers without the hyalinized collagen characteristic of keloids, confirming NS. To date, NS associated with anti-RNA polymerase III antibody-positive SSc has not been reported. The patient was treated with topical PUVA, resulting in reduction of pruritus and softening of nodular lesions. Review of Japanese and international cases indicates that NS commonly arises during active SSc, often in areas of mechanical stress, and shows variable therapeutic response. This case expands the serological spectrum of NS and supports PUVA as a therapeutic option for symptomatic lesions.