Why is a paraneoplastic panel done on LP (Lumbar Puncture)?

From the Guidelines

A paraneoplastic panel is done on LP to identify antibodies associated with underlying neoplasms, which can cause autoimmune encephalitis (AE) 1.

Importance of Paraneoplastic Panel

• The panel helps in diagnosing paraneoplastic neurologic syndromes, which can be associated with various types of cancer, such as small cell lung cancer, thymic neoplasm, breast cancer, and ovarian teratoma 1.
• It is essential to screen for associated neoplasms in adult AE patients, as the symptoms of paraneoplastic and non-paraneoplastic AE can be similar 1.
• The paraneoplastic panel includes testing for antibodies such as NMDAR, GFAP, onconeuronal, LGI1, and AQP4, which can be detected in either CSF or serum 1.

CSF Analysis

• CSF analysis is a crucial step in the diagnosis of AE, and it should include a paraneoplastic panel to identify antibodies associated with underlying neoplasms 1.
• The CSF analysis should also include cell count and differential, protein, glucose, CSF/serum glucose ratio, albumin quotient, IgG index and synthesis rate, oligoclonal bands, and broad viral studies 1.
• In some cases, inflammatory CSF may be the only abnormality found on initial testing, serving as the sole indication for empiric immunotherapy after infection is excluded 1.

From the Research

Paraneoplastic Panel on LP

A paraneoplastic panel is done on Lumbar Puncture (LP) to diagnose paraneoplastic neurological syndromes (PNS) [ 2, 3, 4 ].

• The panel tests for various antibodies associated with PNS, such as anti-Yo (PCA-1) [ 3 ].
• The testing is commonly done on cerebrospinal fluid (CSF) samples obtained through LP [ 2 ].
• The use of paraneoplastic panels has raised concerns about excessive testing and low yield [ 2, 4 ].

Diagnosis of Paraneoplastic Syndromes

The diagnosis of paraneoplastic syndromes requires a neurological workup, including LP with CSF studies, serum and CSF paraneoplastic antibody panel, and neuroimaging [ 3 ].

• The sensitivity of paraneoplastic autoantibody panels is low, ranging from 17-53% [ 4 ].
• The specificity of these panels is higher, ranging from 81-90% [ 4 ].

Lumbar Puncture in Diagnostic Workup

LP is a crucial step in the diagnostic workup of patients with suspected paraneoplastic syndromes [ 3 ].

• LP can help exclude other diagnoses, such as subarachnoid hemorrhage [ 5 ].
• However, LP may not be necessary in all cases, such as in typical patients with idiopathic intracranial hypertension [ 6 ].