Merkel cell carcinoma (MCC) is a rare, aggressive, neuroendocrine tumour that usually occurs in UV-exposed areas of the body and mostly affects elderly individuals. The course is often lethal, as the tumor is often diagnosed only at an advanced stage, metastasises early lymphogenically, and exhibits high recurrence rates. We report a patient who was treated with various immunosuppressive modalities for psoriasis vulgaris (PV) and developed an uncommon MCC in terms of clinical appearance, localization and age. A 49-year-old woman who had been suffering from PV for several years presented to our clinic for a regular follow-up. She had been treated with MTX 15 mg for more than two years, as previous treatments with UVBnb and adalmumab were only short-term and insufficiently effective, respectively. During the visit she casually stated that she had recently noticed a slightly painful swelling on her left thigh. Physical examination revealed a cutaneous-subcutaneous nodule over the lateral portion of the left hip joint that was approximately the size of a hazelnut, firm elastic, freely movable, and tender to palpation. The overlying epidermis was unaffected and exhibited no inflammatory signs. As neither ultrasound examination nor MRI could rule out an abscess, a ruptured epidermal cyst, lipoma or liposarcoma as possible differential diagnoses, the nodule was excised. Surprisingly, histologic analysis revealed a Merkel cell polyoma virus (MCPyV)-positive MCC. Development of Merkel cell carcinoma has been repeatedly reported in immunocompromised patients. Since psoriasis patients are frequently treated with immunosuppressive modalities over many years, physicians should be particularly alert to the appearance of skin lesions of unusual shape and/or atypical location and should, even in younger patients, always consider Merkel cell carcinoma in their differential diagnoses.

ESDR506 - A common remark on an uncommon finding – an unusual presentation of a Merkel cell carcinoma

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.