Anti-Ri antibody associated small cell lung carcinoma.

BACKGROUND: Anti-neuronal antibody Anti-Ri may be positive in patients with paraneoplastic syndrome associated with certain cancer subtypes. Anti-Ri positivity has been associated with breast, gynaecological and small cell lung cancers.

CASE REPORT: A 69 year-old female presented with a sudden decline in cognition requiring hospital admission. She had an extensive medical history including a significant smoking history and bipolar affective disorder for which she was prescribed lithium. Her cognitive decline was initially attributed to diabetes insipidus secondary to lithium therapy. She made a slow but gradual recovery with treatment. Additional investigations revealed positive Anti-Ri antibody. An occult malignancy screen identified enlarged aorto-pulmonary lymph nodes of indeterminate significance. Following discussion at the regional cardiothoracic multidisciplinary team meeting, three monthly surveillance scans were performed. At month 6 an increase in thoracic adenopathy was seen however endobronchial ultrasound guided biopsy failed to identify malignant cells. Further progression with new supraclavicular adenopathy was seen on repeat imaging 6 months later. A fine need aspirate of an enlarged supraclavicular lymph node was diagnostic for small cell lung cancer, staged as TxN3M0 on positron emission tomography. The patient went on to receive sequential chemo-radiotherapy with a truncated course of carboplatin and etoposide and 50 Gy/25 fractions of thoracic radiotherapy.

DISCUSSION: This case suggests that a positive Anti-Ri antibody may predate the development of clinical or radiological evidence of malignancy. If Anti-Ri positivity is identified, strong consideration should be given to screening for malignancy and regular surveillance. This approach may lead to earlier diagnosis and a better outcome for these patients.