Arch Craniofac Surg Vol.20 No.6, 401-404 Archives of Craniofacial Surgery https://doi.org/10.7181/acfs.2019.00542 A case of Merkel cell carcinoma of the head and neck Sangwoo Suk, Merkel cell carcinoma (MCC) is a relatively rare and aggressive cutaneous neuroendocrine malig- Hyun Woo Shin, nancy. It is characterized by high rates of recurrence and metastasis, both to regional lymph nodes Kun Chul Yoon and to distant locations. Its characteristic clinical manifestation is a single, painless, hard, ery- Department of Plastic and thematous nodule on a sun-exposed area, particularly in older men. Surgical management of both Reconstructive Surgery, Kangbuk the primary site and the sentinel lymph node is the standard of care. In this article, we describe Samsung Hospital, Sungkyunkwan the diagnosis and treatment of a case of MCC in the left cheek. University School of Medicine, Seoul, Korea Keywords: Carcinoma / Merkel cells / Skin neoplasm Case Report INTRODUCTION a single, painless, firm, erythematous, and rapidly-growing nodule on her left cheek area (Fig. 1). Due to her age and clini- Merkel cell carcinoma (MCC), first described in 1972 by Toker cal characteristics, an excisional biopsy was performed at the [1], is a relatively rare and aggressive cutaneous neuroendocrine dermatology department, and MCC was diagnosed by histopa- malignancy. It is characterized by high rates of recurrence and thology. Her medical history included surgery for mucoepider- metastasis, both to regional lymph nodes and to distant loca- moid carcinoma of the right salivary gland 20 years previously. tions. MCC most commonly presents as single, painless, hard, The patient was referred to the plastic surgery department of erythematous nodules on sun-exposed areas on the head or our hospital for further evaluation and treatment. Computed neck of older men. It is easily confused with other cancers of tomography (CT) and positron emission tomography (PET) the skin, such as metastases of squamous cell carcinoma, mela- scans were performed preoperatively to evaluate the extent of noma, and other tumors. The current National Comprehensive the primary tumor and to detect metastases. The CT scan re- Cancer Network (NCCN) guidelines recommend wide local vealed a subcutaneous enhancing nodular lesion measuring ap- excision of the primary site with 1–2 cm margins and sentinel proximately 7× 5 mm in the left cheek area, and there was no lymph node (SLN) dissection. However, controversy exists re- evidence of a metastatic lesion in the neck area (Fig. 2A) How- garding the outcomes of MCC treatment, and a multidisci- ever, the PET scan showed a hypermetabolic lymph node in the plinary approach is needed for effective disease management. left side of the neck, at level II (Fig. 2B). The treatment plan was designed using a multidisciplinary CASE REPORT approach involving collaboration of head and neck surgery, he- matology/oncology, radiation oncology, radiology, and nuclear A 77-year-old woman visited a tertiary hospital complaining of medicine teams. Wide excision with regional neck lymph node dissection was planned. Correspondence: Hyun Woo Shin First, the head and neck surgery team performed regional Department of Plastic and Reconstructive Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul neck lymph node dissection. The wide local excision was com- 03181, Korea pleted by the plastic surgery team. The excision extended down E-mail: [email protected] Received October 1, 2019 / Revised December 6, 2019 / Accepted December 16, 2019 to the level of the underlying muscular fascia to ensure a safety Copyright © 2019 The Korean Cleft Palate-Craniofacial Association www.e-acfs.org This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ pISSN 2287-1152 licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. eISSN 2287-5603 401 Suk S et al. Merkel cell carcinoma of the head and neck Fig. 1. The patient presented with a single, painless, firm, erythema- tous, and rapidly growing nodule. Yellow arrow indicated lesion on left cheek area. A B A Fig. 3. A histopathologic examination confirmed Merkel cell carci- noma. Red circle indicated multifocal small tumor nests of monoto- nous round blue cells. (A) H&E, ×12.5; (B) H&E, ×400. the defect area. The radial artery was anastomosed end-to-end with the superior thyroid artery, and the superior thyroid vein was anastomosed end-to-end with the vena comitans. The flap survived without any complications. The patient was dis- charged after 1 month. A histopathologic examination revealed small multifocal tu- mor nests containing monotonous round blue cells in the sub- cutaneous layer. This highly infiltrative tumor was composed of B small clusters of atypical plump spindle cells containing pleo- morphic epithelioid and giant multinucleated cells in varying Fig. 2. A computed tomography scan and positron emission tomog- raphy scan were done. (A) Yellow arrow revealed a subcutaneous en- proportions, numerous mitotic figures, and infiltrative tumor hancing nodular lesion measuring approximately 7×5 mm in the left margins (Fig. 3). The pathology findings were the same as re- check area. (B) Yellow arrow showed a hypermetabolic lymph node ported in the first biopsy. Immunohistochemical staining dem- in the left neck, at level II. onstrated that the tumor cells were positive for cytokeratin-20 (CK-20), with a characteristic paranuclear dot pattern (Fig. 4). margin of 2 cm. Frozen section biopsies revealed no evidence The resection margins were clear, with the closest safety margin of residual tumor cells. After tumor resection, a defect measur- and deepest margin measuring 1.5 cm and 0.1 cm, respectively. ing approximately 5× 4 cm remained on the left anterior cheek Regional lymph node dissection did not reveal any metastases. area. We decided to use a radial forearm free flap to reconstruct One month after excision, radiation therapy (RT) was admin- 402 https://doi.org/10.7181/acfs.2019.00542 Fig. 4. A cytokeratin-20 stain was done and red circle revealed dot- Fig. 5. At a 9-month postoperative follow-up visit, the left cheek like positivity in the tumor cells. flap had completely healed, with minimal scar contracture. istered at the primary site, with a dose of 200 cGy/fraction and cm margins to the investing fascia of muscle when clinically a total dose of 5,400 cGy. RT was completed without any unusu- feasible. Additionally, the NCCN recommends lymph node dis- al adverse reactions. section for clinically evident lymphadenopathy. However, the At a 12-month postoperative follow-up examination, there management of positive SLNs remains controversial. Lemos et was no evidence of systemic relapse on a CT scan. An examina- al. [7] conducted a retrospective analysisof5,823 cases and re- tion of the surgical scar and neck lymph nodes did not reveal ported that 27% of cases presented with nodal disease. Poulsen any local recurrence (Fig. 5). et al. [8] showed that PET scans had sufficiently high sensitivity and specificity for MCC staging. The use of pretreatment PET DISCUSSION scans for staging influenced treatment decisions by allowing upstaging of the disease in 25.9% of MCC patients. In our case, Due to the rarity of MCC and its poorly understood etiology, although we did not perform a preoperative SLN biopsy and no clinical investigations in cases of MCC are often delayed [2]. lymphadenopathy was detected, we carried out a wide local ex- However, the incidence of MCC has been steadily increasing in cision with neck dissection given the hypermetabolic lymph recent years. The overall age-adjusted worldwide incidence of node detected on the preoperative PET scan and because of the MCC based on population studies from the Surveillance, Epi- high incidence of MCC recurrence. demiology, and End Results program in the United States, Numerous retrospective studies and meta-analyses have at- ranges from 0.10 to 1.6 cases per 100,000 people per year [3,4]. tempted to determine whether postoperative RT improves out- Epidemiologists have attributed this rise, in part, to improve- comes in patients with MCC. Unfortunately, the results for both ments in diagnostic techniques, most notably CK-20 immuno- risks of recurrence/progression and survival are inconsistent. histochemical staining [5]. CK-20 is low-molecular-weight ker- Therefore, it is unclear whether postoperative RT provides clin- atin that is normally expressed in gastrointestinal epithelium, ical benefits for node-negative patients. According to the but also in some gastrointestinal and transitional cell carcino- NCCN guidelines, patients treated by wide excision with a neg- mas. CK-20 was the first immunostaining technique used to di- ative SLN biopsy may undergo postoperative RT of the primary agnose MCC reliably [6]. MCC tumors are usually CK-20-posi- site or observation may be considered when the primary tumor tive, making this feature useful for distinguishing MCC from is less than 1 cm. Adjuvant chemotherapy is not recommended other skin cancers. In our case, the tumor cells showed positivi- for local disease. In our case, we considered observation be- ty for CK-20, although it is important to note that CK-20 ex- cause of the small tumor size. However, we administered low- pression has been reported to be negative in 5%–10% of MCC dose RT to reduce the risk of local recurrence. cases. Several large studies have documented the development of re- Surgical management of both the primary site and SLN is the currence in approximately 25%–50% of all cases of MCC [9,10]. standard of treatment for MCC. The current NCCN guidelines Therefore, close clinical follow-up of patients with MCC is im- recommend wide local excision of the primary site with 1 to 2 portant.