A man with paresthesia in both hands – 7 years on
Presentation, history and investigations
In November 2010, the author reported a case of a 63-year-old man with paresthesia in both hands in the Journal of the Society of Physicians of Hong Kong.1 At that time, the patient experienced a mild tingling in both palms, but in about 2–3 weeks, it seemed evident that this was something out of the ordinary. There was no pain, weakness or clumsiness. Apart from mild fatigue, the patient was otherwise well, and continued with his usual busy schedule at work. There was no history of diabetes, hypertension, other chronic diseases, or exposure to toxic chemicals. Side effects of drugs or deficiency states were ruled out.
As reported previously, routine screening blood tests, including thiamine and vitamin B12, were normal. Nerve conduction test showed insignificant results, and there was no evidence of carpal tunnel syndrome or nerve entrapment at other sites. MRI of the cervical spine was normal. Probable diagnoses, including nerve entrapment syndromes and peripheral neuropathies, were ruled out. As the complaint was limited to sensory disturbance without any motor component, a syndrome of sensory neuronopathy was probable. A paraneoplastic neurological syndrome was therefore suspected, with serum anti-Hu (also known as antineuronal nuclear antibody 1 [ANNA 1]) testing positive. This prompted a thorough search for cancer, but low-dose CT, bronchoscopy, gastroscopy, colonoscopy, whole-body MRI, upper abdomen CT with contrast and PET-CT were all negative. There was no definitive conclusion of the condition or pathology at the time. Meanwhile, the patient’s symptoms subsided, and repeated blood tests for anti-Hu were negative on two occasions.
After 7 years of follow-up, the final diagnosis and pathology were confirmed in 2017, with the patient achieving good treatment outcome.
The patient remained healthy with no symptoms during subsequent years of follow-up. He was active and successful in his profession, and was not overly worried about his health.
Follow-up investigations included general blood tests, gastrointestinal endoscopy and abdomen MRI, and lung CT every few years.
In November 2017, lung CT showed a small ground glass opacity measuring 6.8 mm x 5.2 mm in the apex of the right lower lobe of the lung. (Figure) On re-examination of the CT films, the same opacity was found to be present in 2014, but the size was less than 5 mm. A PET-CT scan in November 2017 was negative. After discussion with the radiologist and chest surgeon, it was decided that a biopsy of the lesion would be difficult, but instead a wedge resection of the right lower lobe with frozen section to examine the pathology would be desirable. This was carried out in November 2017. The operation was uneventful. The biopsy showed adenocarcinoma in situ of the lung. The patient recovered well after the operation.
Figure. Lung CT scan in November 2017 showing ground glass opacity in apex of right lower lobe
The syndrome of sensory neuronopathy and detection of anti-Hu antibody in 2010 were very strong indications of the presence of a malignant tumour. In a series of 200 patients positive for anti-Hu, 83.5 percent were found to have cancer, and 90 percent of the cancer cases were small-cell lung cancer.2
Although a thorough search was conducted in 2010, no tumour could be found. However, high vigilance should be maintained and the search effort continued. In patients with paraneoplastic disorders, PET-CT improves cancer detection when other screening tests are negative, particularly in the setting of seropositivity for a neuronal nuclear or cytoplasmic autoantibody marker of cancer. In such patients, an abnormal PET-CT scan can be expected in 20–40 percent of cases, but only 10–20 percent will eventually be found to have cancer due to the high rate of false positive scans.3
In this case, lung cancer was considered probable in 2010. If the lung CT lesion in 2014 had been raised as a matter of concern, the probable course then would have been more frequent scanning to monitor and confirm the increase in size of the lesion, and perhaps efforts to obtain a biopsy. In November 2017, it was confirmed without doubt that the ground glass opacity had been persistent and had grown in size, the step to take a biopsy was omitted, and this had in retrospect been proven the correct approach to take. With the high vigilance of the medical team and cooperation of the patient, the case had come to a happy ending.