Merkel cell carcinoma (MCC) is a rare but highly aggressive form of skin cancer that originates from the neuroendocrine cells in the top layer of the skin. Because MCC has a propensity for rapid growth and metastasis, early detection is crucial for successful treatment and improved prognosis. Identifying the initial signs of this malignancy is important for distinguishing it from more common, benign skin growths.
Physical Characteristics of Early MCC Lesions
The earliest manifestation of Merkel cell carcinoma is typically a single, dome-shaped nodule on the skin surface. This growth feels firm to the touch, distinguishing it from softer cysts or benign fatty tumors. The nodule’s surface is frequently shiny or pearly, and it is usually asymptomatic, meaning it does not cause pain or itching initially.
The color of the early lesion is variable, often appearing pink, red, purple, or violaceous (reddish-blue). Sometimes, the nodule may simply be skin-colored, making it challenging to spot, especially on fairer skin. Unlike many other skin malignancies, MCC lesions generally lack ulceration, crusting, or scaling when they first appear. These lesions typically measure between 0.7 and 1.2 centimeters in diameter at diagnosis.
Common Locations and Rapid Growth
Merkel cell carcinoma most frequently develops in areas of the skin that have received significant sun exposure over a person’s lifetime. The head and neck are the most common sites, accounting for approximately 53% of cases, followed by the arms and legs, which make up about 35% of occurrences. The trunk and other sun-shielded areas can also be affected, especially in individuals with darker skin tones.
One of the most significant features of MCC is its rapid growth pattern, which is an important factor in its early identification. Patients frequently report that the lesion has noticeably increased in size over a period of just a few weeks to months. This rapid growth rate sets MCC apart from slow-growing basal cell carcinomas or benign growths, which may take years to change.
Primary Risk Factors
The development of Merkel cell carcinoma is strongly linked to a combination of environmental and biological factors, which tend to affect a specific demographic. Advanced age is a major risk factor, with most patients diagnosed over the age of 50, and the majority of cases occurring in people in their 70s and 80s. Chronic exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds significantly contributes to the risk.
The Merkel cell polyomavirus (MCPyV) is considered a primary cause, detected in approximately 80% of MCC tumors. Although MCPyV is common in the general population and often causes no symptoms, its integration into the host cell’s DNA is a necessary step in the formation of the cancer. Immunosuppression is another substantial factor, as individuals with weakened immune systems, such as organ transplant recipients or those with HIV, face an elevated risk.
Immediate Steps Following Discovery
Anyone who discovers a new or changing skin lesion that matches the description of an early Merkel cell carcinoma should seek immediate medical consultation. Schedule an appointment with a dermatologist or a physician experienced in skin cancer diagnosis, as the aggressive nature of MCC demands prompt attention. The rapid growth of the lesion is a warning sign that should not be ignored, even if the bump is painless.
The diagnostic process begins with a physical examination, which includes a visual inspection of the lesion and palpation of nearby lymph nodes for signs of swelling. A definitive diagnosis requires a skin biopsy, where tissue is removed for microscopic examination by a pathologist. Specialized laboratory tests, such as immunohistochemistry with markers like Cytokeratin 20 (CK20), are then used to confirm the presence of MCC cells and distinguish it from other skin cancers.