We report the case of a 70-year-old Japanese man who was referred from a local urologist because of acute urinary retention (detrusor underactivity revealed by a urodynamics examination). A neurogenic urinary retention workup failed to reveal the aetiology, but a spinal tap incidentally showed occult meningeal reaction with positive oligoclonal band. The patient had no headache, nausea/vomiting or fever. Considering his clinical laboratory findings, his neural lesions seemed to involve the meninges and spinal cord, suggestive of ‘form fruste’ meningitis-retention syndrome. When clinicians encounter patients with urinary retention of undetermined aetiology, a spinal tap should be considered.

If meningitis is suspected, head computed tomography is performed before cerebrospinal fluid collection. Crown dens syndrome can be diagnosed using simultaneous CT scans of the head and neck. Thus, unnecessary CSF tap test can be avoided.

Rationale: Although IgG4-related disease (IgG4-RD) can affect various organs, its association with a cardiac mass is exceptionally rare. Here, we report a case of a woman with IgG4-RD and a cardiac mass and discuss 10 similar cases reported previously. Patient concerns: A 65-year-old woman was referred to our hospital for chest discomfort and back pain. Diagnoses: In accordance with the 2019 ACR/EULAR diagnostic criteria for IgG4-RD, she was diagnosed with IgG4-RD based on dense lymphocytic infiltration on histopathology, IgG/IgG4-positive cell ratio <40%, >10/hpf IgG4-positive cells on immunostaining, and paraspinal zone soft tissue lesions in the chest. Interventions: An external pacemaker was implanted for the complete atrioventricular block on the electrocardiogram. After the diagnosis of IgG4-RD, she was treated with glucocorticoids and rituximab. Outcomes: She remains under observation without disease recurrence. Lessons: IgG4-RD are usually treated with glucocorticoids; however, in cases of a cardiac mass, life-threatening complications may occur and surgery is often needed. Combination therapy with glucocorticoids and rituximab may be effective even in patients with IgG4-RD and cardiac mass, which may avoid the need of invasive treatments, such as surgery.