Evaluating patients with suspected paraneoplastic retinopathy accompanying small cell carcinoma
Immunoblot (IB)
Anti-CAR
CAR
Carcinoma-associated retinopathy
Serum
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.
See Specimen Required
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 28 days | |
Frozen | 28 days | ||
Ambient | 72 hours |
Evaluating patients with suspected paraneoplastic retinopathy accompanying small cell carcinoma
Patients with recoverin autoimmunity present with insidious onset vision change, often night-vision loss, floaters, and constricted vision, that can rapidly progress to blindness. On ophthalmologic examination, there are features of non-inflammatory retinopathy; retinal and optic nerve head pallor/atrophy, constricted visual fields and flat electroretinogram (ERG), but without anterior chamber disease, which is encountered with CRMP-5 paraneoplastic ophthalmitis. Small cell (pulmonary or extrapulmonary) or neuroendocrine carcinoma should be sought. Trials of immunotherapy could be attempted to improve vision, though generally this is not successful.
Negative
Seropositivity is consistent with a diagnosis of paraneoplastic retinopathy. Small cell carcinoma (pulmonary or extrapulmonary) and neuroendocrine carcinoma should be considered.
A negative result does not exclude paraneoplastic retinopathy, other autoimmune retinopathy, or cancer.
At Mayo Clinic,(1) recoverin-IgG antibody was detected in no controls and 2/33 suspected autoimmune/paraneoplastic retinopathy patients (6%); both were men with painless vision loss, detected 2 to 4 months before cancer detection. Patient 1, an 85 year-old smoker, progressed to light perception only bilaterally within 1 month. Small cell lung carcinoma was detected. Patient 2, a 66 year old non-smoker, had insidious progression of vision loss, ataxia, and myelopathy (and also harbored P/Q- and N-type calcium channel antibodies). Metastatic neuroendocrine carcinoma was detected. Both patients had bilateral optic nerve and retinal atrophy (non-inflammatory appearing) and flat electroretinograms. Neither patient had vision improvements despite cancer treatment and immunotherapy; both died from cancer within 2 years of diagnosis. During clinical evaluation, 25/33 retinopathy patients (including patients 1 and 2) were tested for recoverin antibody in an outside laboratory, and were reported negative in all but patient 1.
1. McKeon A, Lopez A, Lachance D, et al: Recoverin antibody: Ophthalmologic and oncologic significance. Neurology. 2016;86:(16 Supplement)
Euroline (line-blot from Euroimmun, AG). All steps are performed at ambient temperature (18-28 degrees C) utilizing the EUROBlot One instrument. Diluted patient serum (1:12.5) is added to test strips (strips containing recombinant antigen manufactured and purified using biochemical methods) in individual channels and incubated for 30 minutes. Positive serum samples will bind to the purified recombinant antigen and negative serum samples will not bind. Strips are washed to remove unbound serum antibodies and then incubated with anti-human IgG antibodies (alkaline phosphatase-labelled) and incubated for 30 minutes. The strips are again washed to remove unbound anti-human IgG antibodies and nitroblue tetrazolium chloride/5-bromo-4-chloro-3-indolylphosphate (NBT/BCIP) substrate is added. Alkaline phosphatase enzyme converts the soluble substrate into a colored insoluble product on the membrane to produces a black band. Strips are digitized via picture capture on the EUROBlot One instrument and evaluated with the EUROLineScan software.(Instruction manual: EUROLINE Neuronal Antigens Profile 72 (IgG). EUROIMMUN Medizinische Labordiagnostika AG)
Monday through Friday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
84182
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
RCVBS | Recoverin Immunoblot, S | 83003-4 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
610009 | Recoverin Immunoblot, S | 83003-4 |