ImmunoglobulinG4 (IgG4)-related sclerosing disease (ISD) has been increasingly recognized as a multisystem fibro-inflammatory disorder. We report a case of a 69 year-old male with lung opacities, history of autoimmune pancreatitis (AIP) and elevated IgG4 level.
A 69 year-old male with remote smoking history was referred for evaluation of a pulmonary mass. His past medical history was significant for pernicious anemia, AIP, and parotid and submandibular lymphadenopathy. He developed acute abdominal pain 6 months prior to his visit to our clinic. He was admitted to a local hospital and treated with antibiotics for diverticulitis. During the hospitalization, a computed tomography (CT) scan of the abdomen/pelvis incidentally demonstrated bilateral focal ground glass opacities in lower lobes. He had no pulmonary symptom. A subsequent chest x-ray (CXR) one month later showed resolution of the right lower lobe infiltrate, but a persistent left lower lobe (LLL) focal infiltrate. A repeat CT scan in 4 months showed worsening of a 3.5 × 2.5 cm LLL opacity. On examination, his vital signs were stable and physical examination revealed palpable parotid and submandibular lymphadenopathy. General laboratory testing was normal, except for elevation of aspartate aminotransferase (224 U/L). A positron emission tomography (PET)/CT scan demonstrated hypermetabolic LLL lesion, left hilar and paratracheal lymph nodes. Subsequently, a transbronchial biopsy and bronchoalveolar lavage were non-diagnostic. Hilar and paratracheal lymph nodes were negative for malignancy. The patient received antibiotics and discharged home. A repeat CT scan one month after the antibiotic therapy showed larger and denser infiltrate 5.0 x 3.5 cm in size, mass-like consolidation. Left hilar and paratracheal lymph nodes were unchanged. He underwent video-assisted cervical mediastinoscopy and left thoracoscopy with biopsies. Lymph nodes were negative for malignancy. Wedge resection of the infiltrate revealed fibrosis and plasma cell-rich inflammation along with organizing pneumonia and moderate cellular nonspecific interstitial pneumonia. Immunostains revealed a marked increase in IgG4-positive plasma cells (231 per high power field) with the high IgG4/IgG ratio (72%). Kappa and lambda stains showed polytypic pattern of light chains in plasma cells. Serum IgG4 was elevated to 1150 mg/dL (reference range: 8.0–140.0 mg/dL). The patient was diagnosed with IgG4-related lung disease and started on Prednisone 40 mg daily, then discharged home. A repeat CXR one month later showed complete resolution of the LLL lesion.
ISD has been recently coined to describe a multi-system steroid-responsive fibro-inflammatory disorder, characterized by an elevation in serum IgG4 levels and tissue infiltration with abundant IgG4-positive plasma cells . AIP is considered to be the pancreatic manifestation of ISD. A lung mass-like lesion is one type of pulmonary manifestation described in the literature in association with elevation of IgG4 levels with or without concurrent AIP . Differential diagnosis of this mass-like infiltrate included bronchioalveolar carcinoma, lymphoma, and non-neoplastic disorder, such as cryptogenic organizing pneumonia. The measurement of serum IgG4 levels in the early stage of presentation could have raised the clinical suspicion for IgG4-related lung disease.
The diagnosis of IgG4-related lung disease should be considered in a patient with a history of AIP and new pulmonary findings. The radiological features can mimic malignant or other focal inflammatory processes. Increase awareness of ISD and measurement of serum IgG4 levels could facilitate diagnosis and prevent invasive procedures in the appropriate clinical setting. The natural history, incidence, and pathophysiology of IgG4-related lung disease is not well known and further studies are warranted.
Hiroshi Sekiguchi, No Financial Disclosure Information; No Product/Research Disclosure Information