Pulmonary Nodular Lymphoid Hyperplasia: Reviewing a Lung Cancer Mimicker.

[BACKGROUND] Pulmonary nodular lymphoid hyperplasia is a rare benign lymphoproliferative disorder. Patients are commonly asymptomatic. Its radiological presentation is characterized by peripheral single nodular lesion, multiple nodules or mass-like consolidation. Therefore, it can mimic other more frequent pulmonary diseases, such as lung cancer and pulmonary lymphoma. The diagnosis is often late, relying on histopathological findings.

[CASE PRESENTATION] We report a case of a 66-year-old woman who presented with cough and upper respiratory tract symptoms. Chest CT revealed a mass in the right lower lobe, mediastinal and hilar enlarged lymph nodes and multifocal ground-glass and part solid nodules. PET-CT findings were concerning for primary lung malignancy. She underwent transbronchial needle aspiration biopsy of the enlarged lymph nodes and pulmonary mass. The results were negative for malignancy, but immunophenotyping by flow cytometry was concerning for a lymphoproliferative disorder. For this reason, a percutaneous CT-guided transthoracic core needle biopsy of the mass was performed. Immunophenotypic features of lymphoma were not identified. Overall findings were suggestive of nodular lymphoid hyperplasia. The follow-up chest CT showed near complete resolution of the mass with a residual ground-glass lesion and stability of the enlarged lymph nodes, ground-glass and part solid nodules.

[CONCLUSION] Pulmonary nodular lymphoid hyperplasia is an uncommon lung disorder, usually detected incidentally on chest imaging. Its radiological features can mimic lung cancer and other more prevalent pulmonary diseases. Therefore, a multidisciplinary approach, including histopathological confirmation is essential for an accurate diagnosis. Although rare, it should be considered in the differential diagnosis of pulmonary malignancies.