pseudotumor

Pseudotumor is a nonneoplastic condition or lesion that mimics a tumor in clinical presentation or imaging. The term has been used in several organ systems to describe inflammatory or mass-like processes that are not true cancers, and its exact meaning can vary by specialty. In many cases, pseudotumor represents an inflammatory or immune-mediated process rather than a true neoplasm.

One well-known example is pseudotumor cerebri, more accurately termed idiopathic intracranial hypertension. This condition features elevated intracranial pressure without a brain tumor and may present with headaches, transient visual obscurations, and papilledema. Diagnosis relies on neuroimaging that is often nondefinitive and on lumbar puncture showing elevated opening pressure with normal CSF composition. Management focuses on reducing intracranial pressure and may include weight loss, acetazolamide, other diuretics, or surgical options in refractory cases.

Orbital pseudotumor, or idiopathic orbital inflammatory disease, is another common usage. It presents with painful eye movements, periorbital swelling, and sometimes proptosis. Imaging aids evaluation, but diagnosis is often clinical, supported by response to corticosteroids. It must be distinguished from infections, neoplasms, and thyroid eye disease; treatment typically involves steroids and, in some cases, immunosuppressive therapy.

Inflammatory pseudotumor can also occur in other sites such as the lung, liver, or abdomen. These lesions are characterized by inflammatory cell infiltrates and fibrous tissue and can mimic malignant tumors on imaging. Management varies by location and may include observation, anti-inflammatory therapy, or surgical excision.

Notes: the term pseudotumor is evolving, with many conditions now named more specifically by site and histology. Imaging and, when needed, biopsy help distinguish pseudotumors from true neoplasms.