A Spontaneous Regression of an Isolated Lymph Node Metastasis from a Primary Unknown Merkel Cell Carcinoma in a Patient with an Idiopathic Hyper-Eosinophilic Syndrome

• Published in: The American journal of case reports 2018-12, Vol.19, p.1437-1440
• Main Authors: Longo, Raffaele, Balasanu, Oana, Chastenet de Castaing, Mathilde, Chatelain, Eric, Yacoubi, Mohammed, Campitiello, Marco, Marcon, Nathalie, Plastino, Francesca
• Format: Article
• Language: English
• ISSN: 1941-5923; 1941-5923
• DOI: 10.12659/AJCR.911840

BACKGROUND Merkel cell carcinoma (MCC) is a rare, aggressive primary cutaneous neuroendocrine tumor frequently associated with Merkel cell polyomavirus infection. Despite its aggressiveness, a few reports of spontaneous MCC regression have been described in the literature, most of them following incisional biopsy supporting a hypothetical role of surgery-induced inflammation in the process of regression. CASE REPORT We report a case of 69-year-old Caucasian male who was followed for an idiopathic hyper-eosinophilic syndrome. A positron emission tomography (PET) scan documented a hyper-metabolic, left, inguinal adenopathy, histologically corresponding to a metastasis of a poorly differentiated neuroendocrine carcinoma. This lesion spontaneously regressed at clinical examination and radiological imaging. After its excisional dissection, histology was negative. Five months later, a nearby adenopathy reappeared. The patient underwent another excisional biopsy. Histology and immunohistochemistry were compatible with a lymph node metastasis of a MCC. As the patient refused radical surgery, a regional radiotherapy was performed. As of a follow-up at 10 months, he was alive and free of tumor recurrence. The hyper-eosinophilic syndrome was stable; however, the serum levels of chromogranin-A were inexplicably elevated in the absence of any tumor evidence at the PET scan. CONCLUSIONS The particularity of this case relies on the rarity of MCC complete spontaneous regression in a patient without a primary tumor and with a synchronous, idiopathic hyper-eosinophilic syndrome.