Chemotherapy-Responsive Nodal Inflammatory Pseudotumor Initially Misdiagnosed as Metastatic Carcinoma: A Diagnostic and Therapeutic Dilemma

Abstract Background: Nodal inflammatory pseudotumor (IPT) is a rare benign lesion that can closely mimic malignancy both clinically and histologically. Owing to its nonspecific presentation, diagnosis is often one of exclusion and requires a high index of suspicion supported by immunohistochemical (IHC) analysis. Case Presentation: A 30-year-old woman presented with bilateral inguinal lymphadenopathy. She was initially treated for tuberculosis and subsequently diagnosed with metastatic poorly differentiated carcinoma based on lymph node biopsy. The patient received paclitaxel–carboplatin chemotherapy, resulting in a marked clinical and radiological response. However, final immunohistochemical (IHC) analysis of the same biopsy specimen revealed nodal inflammatory pseudotumor. Despite IPT being a benign condition, the patient demonstrated a significant response to cytotoxic chemotherapy administered under the presumed diagnosis of carcinoma. Conclusion: Nodal inflammatory pseudotumor can closely mimic infection or malignancy, making immunohistochemistry essential before initiating cytotoxic therapy. This case highlights both the diagnostic challenge of IPT and an unusual observation of response to cytotoxic chemotherapy in a histologically benign entity. Keywords: Inflammatory pseudotumor, Nodal pseudotumor, Misdiagnosis, Chemotherapy response, Inguinal lymphadenopathy