IgG4-related pleuritis diagnosed by local anesthesia thoracoscopy; a case report and literature review

Abstract

IgG4-related pleuritis is rare in patients with IgG4-related diseases (IgG4RD). We report a case of IgG4-related pleuritis diagnosed in a 77-year-old Japanese man with right pleural effusion. The pleural effusion exhibited lymphocyte-predominant exudates with elevated adenosine deaminase (ADA) and IgG4 levels, along with the presence of plasma cells. A pleural biopsy via local anesthesia thoracoscopy (LAT) confirmed the diagnosis of IgG4-related pleuritis, and the patient was treated with prednisolone and azathioprine. Although ADA is a well-known useful marker for diagnosing tuberculous pleuritis, a review of 14 reported cases of IgG4-related pleuritis demonstrated a positive correlation between IgG4 and ADA in pleural effusion (ρ = 0.705, p < 0.05), suggesting that ADA levels could be elevated in IgG4-related pleuritis. Furthermore, all cases with available cytology reports showed the presence of plasma cells, indicating that detecting plasma cells could aid in diagnosis. Pleural biopsy remains the gold standard for the diagnosis of IgG4-related pleuritis. LAT is a safe and effective diagnostic procedure for older patients, enabling direct visualization and biopsy of pleural lesions without intubation. IgG4-related pleuritis presents with specific findings, including dense white granulomatous lesions, vesicular nodular changes, nonspecific inflammatory changes, and pleural thickening. IgG4-positive plasma cells can be detected even in biopsies with diffuse, nonspecific findings. Therefore, LAT is a valuable and safe tool for diagnosing IgG4-related pleuritis. In conclusion, exudative pleural effusion with elevated ADA levels should prompt the consideration of IgG4-related pleuritis in the differential diagnosis. LAT is a minimally invasive and highly accurate diagnostic tool for IgG4-related pleuritis.

Keywords: ADA; IgG4-related disease; IgG4-related pleuritis; Local anesthesia thoracoscopy; Medical thoracoscopy; Plasma cell; Pleuroscopy.

Graphical abstract

Fig. 1

Chest radiography and computed tomography images. A: Right-sided pleural effusion; B: Right-sided pleural effusion and bronchovascular bundle thickening.

Fig. 2

Microscopic findings from thoracoscopy. A: The pleura shows diffuse white pleural thickening and erythema. Vascular proliferation and capillary dilation is seen in the parietal pleura. B: Areas of redness on the parietal pleura showing vascular proliferation and capillary dilation on the narrow-band image. C: A polypoid lesion with a smooth surface is observed on the visceral pleura.

Fig. 3

Pathological findings of pleural biopsy. A: Hematoxylin and Eosin staining ( × 400) reveals severe infiltration of inflammatory cells (lymphocytes and plasma cells) and fibrosis; B: CD 138 staining ( × 100); C: IgG staining ( × 200); D: IgG4 staining ( × 200) reveals more than 20 IgG4-positive plasma cells per high-power field. The IgG4/IgG ratio was difficult to assess due to strong co-staining in the surrounding stroma.

Fig. 4

Correlation between IgG4 and ADA levels in pleural effusion. Scatter plot of Spearman's rank correlation between IgG4 and ADA levels in pleural effusion.