Rare Type A Lymphomatoid Papulosis Initially Presenting as a Giant Ulcer: A Case Report and Literature Review

Xiangru ChenQingling ZhangJingtong ZhaoYuxi Jia^*Lin An^*

• China-Japan Union Hospital, Jilin University, Changchun, China

Background: Lymphomatoid papulosis (LyP) is a rare, chronic, recurrent, self-healing, indolent cutaneous lymphoproliferative disorder. Histologically, it resembles malignant lymphoma; however, its clinical manifestations are predominantly characterized by benign behaviors, including recurrent papules, nodules, and necrotic lesions. Case Presentation: We report a case of a middle-aged female who initially presented with a giant ulcer on the right foot and was surgically treated at another hospital as a keratoacanthoma (KA). Over subsequent months, she developed scattered papules and nodules on the trunk and limbs. A comprehensive clinical and histopathological reassessment confirmed a diagnosis of LyP Type A. Notably, the initial ulcerative lesion represented an atypical feature of LyP rather than a conventional KA. Finally, the patient was successfully treated with methotrexate and interferon, resulting in complete resolution of the skin lesions without recurrence. Conclusions: In summary, this case highlights that a giant ulcer exhibiting pseudoepitheliomatous hyperplasia (PEH) in histopathology may indicate LyP. Careful assessment for atypical lymphocytic infiltration and further immunohistochemical evaluation are essential for accurate diagnosis. When single clinical or histopathological findings are insufficient to provide a comprehensive understanding of the disease, thorough evaluation and dynamic monitoring are critical for diagnosing and managing complex cases. Dupont in Germany and subsequently named LyP by Macaulay in 1968(1). LyP and primary cutaneous anaplastic large-cell lymphoma (C-ALCL) both belong to the category of cutaneous CD30+ T-cell lymphoproliferative disorders and exhibit highly similar histological features and immunophenotypes.We report the case of a 57-year-old Chinese woman with LyP Type A, who initially presented with a large ulcer on the dorsum of her right foot, followed by the subsequent development of scattered papules and nodules on the trunk and limbs. Pathological examination of the ulcer on the dorsum of the foot revealed PEH, which had been previously misdiagnosed as KA. Following a comprehensive evaluation of the clinical manifestations and relevant pathological examinations, the patient was ultimately diagnosed with LyP. The KA-like changes were determined to be reactive epidermal hyperplasia, which was a part of the disease evolution. Atypical initial clinical and pathological presentations significantly increase the likelihood of misdiagnosis, underscoring the diagnostic challenges inherent in LyP.