LEMS Likely Triggered by Rare Skin Cancer in Case Study

Lambert-Eaton myasthenic syndrome (LEMS) may be associated with a rare type of skin cancer called Merkel cell carcinoma (MCC), according to a case study which also highlighted the need for multidisciplinary care in such complex cases.

The case report, “Lambert-Eaton Myasthenic Syndrome and Paraneoplastic Cerebellar Degeneration Associated with Merkel Cell Carcinoma with Unknown Primary: A Case Report,” was published in the journal Acta Dermato-Venereologica.

Different types of paraneoplastic syndromes, including LEMS, have been associated with MCC, a rare and aggressive skin cancer whose incidence has been steadily increasing. Paraneoplastic syndromes comprise a group of rare disorders that are triggered by the body’s immune response against a tumor.

In the report, researchers at the University of Turin in Italy described the case of a 59-year-old man who had two types of paraneoplastic syndromes associated with MCC.

The patient went to the hospital after experiencing muscle weakness, difficulty walking, diplopy (double vision), and nystagmus (repetitive, uncontrolled eye movements) for the past two weeks.

A battery of laboratory and clinical tests revealed the presence of self-targeting antibodies and abnormal nerve-muscle communication, both consistent with a diagnosis of LEMS. The patient was given symptomatic treatment with fampridine (sold as Fampyra in the EU and Ampyra in the U.S.), an approved medication used to improve walking in people with multiple sclerosis, which partially improved his condition.

Additional imaging tests revealed the presence of lesions in the patient’s left inguinal lymph nodes. Lymph nodes are immunological organs located throughout the body, and inguinal lymph nodes are located in the groin.

A lymph node biopsy and subsequent laboratory testing confirmed the presence of rogue cancer cells with features consistent with those of MCC. Yet, no skin lesions or any other signs of a tumor were found in the patient’s body. The researchers speculated the lesions in the patient’s lymph nodes might have originated from another tumor somewhere else, which was missed upon examination or had gone into remission on its own before the patient was examined.

The patient underwent radiation therapy, as his overall health status did not allow for radical surgical treatment. Imaging tests performed two months later revealed he was in remission.

After six months, his walking ability had improved. However, he still experienced double vision, repetitive and uncontrolled eye movements, and coordination issues. These persistent symptoms were deemed to be related to paraneoplastic cerebellar degeneration (PCD), a paraneoplastic syndrome in which the body’s immune system erroneously launches an inflammatory attack on cells in the brain.

In this case, the researchers noted that LEMS and PCD were probably triggered by the patient’s immune system when trying to fight against MCC.

“This case report highlights the importance of multidisciplinary management; dermatologists should be aware of the possible paraneoplastic syndromes associated with MCC,” they concluded.