Researchers Find Link Between LEMS and MCC

Sometimes, in the midst of performing medical research, researchers may discover an association between two conditions. According to Lambert Eaton News, University of Turin researchers recently determined a link between Lambert-Eaton myasthenic syndrome (LEMS) and Merkel cell carcinoma (MCC). While these conditions have previously been linked in the past, researchers now recognize that MCC may actually trigger LEMS to develop. Check out the full findings published in Acta Dermato-Venereologica.

LEMS Research

In the past, researchers have linked MCC to the development of paraneoplastic syndromes. According to the National Institute of Neurological Disorders and Stroke (NINDS), paraneoplastic syndromes such as LEMS are:

rare disorders that are triggered by an abnormal immune system response to a cancerous tumor known as a “neoplasm.” Paraneoplastic syndromes are thought to happen when cancer-fighting antibodies or white blood cells (known as T cells) mistakenly attack normal cells in the nervous system.

Since MCC is such an aggressive form of cancer, it makes sense that these conditions would appear.

Case Report

The most recent research, in the form of a case report, explored a 59-year-old male with MCC who was also showing additional symptoms associated with paraneoplastic syndromes. When he first appeared at the hospital, he had been experiencing a variety of symptoms over a 2-week period, which included:

  • Double vision (diplopia)
  • Involuntary and uncontrolled eye movements
  • Weak muscles
  • Loss of coordination
  • Lymph node lesions
    • Note: In particular, the lesions were discovered on the left inguinal (groin) lymph nodes. Unfortunately, researchers could not find a tumor or skin lesions, which would normally relate to MCC. This made researchers believe that the patient had either achieved remission separately or that the tumor had not yet been found.
  • Difficulty walking

After some testing, researchers determined that the patient had Lambert-Eaton Myasthenic Syndrome (LEMS). Ultimately, he was treated with fampridine and radiation. Through this, some symptoms improved, he entered into remission and was better able to walk after 6 months.

But while he was able to walk better, his other symptoms still remained. After performing additional testing, researchers determined that the man had paraneoplastic cerebellar degeneration (PCD). According to the American Autoimmune Related Diseases Association (AARDA), PCD is:

a rare neurological disorder characterized by a widespread loss of Purkinje cells associated with a progressive pancerebellar dysfunction.

Ultimately, researchers determined that the immune response to MCC triggered both the PCD and LEMS. As a result, researchers suggest that those treating MCC should be aware of potential disorders that may arise.

Lambert-Eaton Myasthenic Syndrome (LEMS)

Lambert-Eaton Myasthenic Syndrome (LEMS) is an autoimmune disorder in which the immune system mistakenly attacks nerve cells and muscles (the neuromuscular junction). Altogether, the condition was first discovered sometime between the 1950s and 1960s. In approximately 60% of diagnoses, patients with LEMS have another condition, such as MCC or small-cell lung cancer (SCLC). When the immune system activates to fight the cancer, it mistakenly targets these healthy nerve fibers, causing a variety of health issues.

Additionally, approximately 90% of patients with LEMS have high voltage-gated calcium channel (VGCC) protein in their bodies. Normally, VGCC helps calcium move into nerve cells and release acetylcholine (ACh), which plays a role in muscle contractions.

Symptoms of LEMS include:

  • Dry mouth and eyes
  • Unintended weight loss
  • Changes in blood pressure
  • Blurred vision
  • Difficulty walking, talking, swallowing, chewing, lifting objects, or performing other similar functions
  • Erectile dysfunction
  • Eyelid or head drooping
  • Muscle weakness or fatigue, particularly in the arms and legs
  • Dizziness
  • Bladder and bowel changes

Merkel Cell Carcinoma (MCC)

Also known as neuroendocrine carcinoma of the skin, Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer. As the Skin Cancer Foundation explains:

Merkel cells are located deep in the top layer of skin [and] are connected to nerves, signaling touch sensation as “touch receptors.”

Risk factors include excessive sun exposure, age (50+), having a history of skin cancer, being immunocompromised, or having lighter skin. Typically, MCC first appears on the head, neck, face, or other sun-exposed areas. It is often a red, blue, purple, or flesh-colored nodule. While the nodule grows rapidly, it is often painless. An estimated 3,500 Americans are diagnosed with MCC each year. Unfortunately, the cancer has a high risk of spreading or recurring within 2-3 years of diagnosis.

MCC is extremely malignant and aggressive. When it begins to metastasize, it often moves first to the lymph nodes. However, MCC can also spread to the liver, lungs, brain, or bones. Altogether, MCC is around 3-4x more fatal than melanoma. But with early diagnosis and treatment, MCC can be treated.

So if you notice any of the following, please see your doctor immediately:

  • A painless red, blue, purple, or flesh-colored nodule that is growing in size
  • A new mole, freckle, or bump
    • Note: Even if not new, keep an eye on any moles, bumps, freckles, or other nodules that are changing in size, shape, or color; experiencing rapid growth; or bleeding easily.
Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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