The reversed halo sign is observed in a broad spectrum of lung diseases, most commonly organising pneumonia, but it has not been reported in pulmonary nodular lymphoid hyperplasia. Herein, we describe the first case of pulmonary nodular lymphoid hyperplasia presenting with a reversed halo sign.

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. 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. 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.

Immune receptor translocation-associated 1 (IRTA1) expression, which has recently been shown to be highly specific for marginal zone lymphoma, is found in only a subset of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). In this study, we examined whether IRTA1 expression in MALT lymphoma was dependent on anatomic location. IRTA1 immunohistochemistry was performed in 60 cases of extranodal MALT lymphoma, arising at breast, conjunctiva, lung, salivary gland, skin, and stomach (10 cases each). Expression was also scored with respect to detailed morphologic features. IRTA1 staining was identified in 25 (42%) cases, ranging from 9 (90%) of 10 in lung to 2 (20%) of 10 in gastric MALT lymphoma. IRTA1 staining was not characteristic of specific morphologic features, as it was absent in most lymphoepithelial lesions, perifollicular cells, cells with overt monocytoid cytology, and plasmacytic cells. IRTA1 expression was also identified in 5 (50%) of 10 cases of pulmonary nodular lymphoid hyperplasia. IRTA1 expression is heterogeneous in extranodal MALT lymphoma. Staining for IRTA1 is not characteristic of specific morphologic features, but varies with the anatomic site of disease. Knowledge of site-specific differences in MALT lymphomas will facilitate diagnosis in routine clinical practice.

To investigate the clinical and radiographic features of PNLH and the relationship with pathologic features. A total of 11 patients in whom PNLH was confirmed in our department were retrospectively studied. The clinical and radiographic features were extracted and analyzed, and we also discussed the relationship between radiologic and pathologic features. Of the 11 patients with PNLH, 5 were discovered incidentally, while 4 presented with chest symptoms. Laboratory tests showed no specificity and the lesions were located under the pleura with an adjacent pleural indentation. Most lesions were solid, with some showing signs of spiculation or spiculate protuberance. In some cases, hypodense areas and vocules were visible. The enhanced scan showed marked enhancement, but most had no lymph node enlargement, and there was no pleural effusion. The clinical manifestations of PNLH are nonspecific and the imaging features overlap with those of malignant lung tumors, and the diagnosis depends on pathologic examination.

Pulmonary nodular lymphoid hyperplasia (PNLH) is a rare pulmonary lymphoproliferative disease characterized by the absence of specific clinical and imaging features. Consequently, diagnosis relies heavily on postoperative pathological examination, which often leads to preoperative misdiagnosis. Here, we report an atypical case of PNLH in a 57-year-old female patient who was admitted to hospital after a pulmonary nodule was discovered during a routine physical examination two days earlier. Chest CT scan revealed a mixed ground-glass nodule in the apicoposterior segment of the left upper lobe, with lobulation and spiculation. These imaging findings initially suggested a diagnosis of pulmonary malignancy. However, pathological examination and IgH gene rearrangement analysis of the resected tissue ultimately confirmed the diagnosis of PNLH. 肺结节性淋巴组织增生（PNLH）是一种肺内少见的淋巴组织增生性疾病，其临床和影像学上没有特定征象，诊断很大程度上取决于术后病理检查，因此术前易误诊。本文报道1例非典型的PNLH病例：患者女，57岁，因体检发现肺结节2 d入院。胸部CT显示左肺上叶尖后段混合磨玻璃结节，可见分叶、毛刺，基于此影像特征初步诊断考虑为肺部恶性肿瘤。术后切除组织行病理学及IgH基因克隆性重排检测分析，最终诊断为PNLH。.