Jour George, Aung Phyu P, Rozas-Muñoz Eduardo, Curry Johnathan L, Prieto Victor, Ivan Doina
Department of Pathology, Dermatopathology Section, The University of Texas MD, Anderson Cancer Center, Houston, Texas.
Department of Dermatology, Hospital de la Santa Creu I Sant Pau, Universitat Autònoma, Barcelona, Spain.
J Cutan Pathol. 2017 Aug;44(8):684-691. doi: 10.1111/cup.12966. Epub 2017 Jun 13.
Merkel cell carcinoma (MCC) is a rare but aggressive cutaneous carcinoma. MCC typically involves dermis and although epidermotropism has been reported, MCC strictly intraepidermal or in situ (MCCIS) is exceedingly rare. Most of the cases of MCCIS described so far have other associated lesions, such as squamous or basal cell carcinoma, actinic keratosis and so on. Herein, we describe 3 patients with MCC strictly in situ, without a dermal component.
Our patients were elderly. 2 of the lesions involved the head and neck area and 1 was on a finger. All tumors were strictly intraepidermal in the diagnostic biopsies, and had histomorphologic features and an immunohistochemical profile supporting the diagnosis of MCC. Excisional biopsies were performed in 2 cases and failed to reveal dermal involvement by MCC or other associated malignancies.
Our findings raise the awareness that MCC strictly in situ does exist and it should be included in the differential diagnosis of Paget's or extramammary Paget's disease, pagetoid squamous cell carcinoma, melanoma and other neoplasms that typically show histologically pagetoid extension of neoplastic cells. Considering the limited number of cases reported to date, the diagnosis of isolated MCCIS should not warrant a change in management from the typical MCC.
默克尔细胞癌（MCC）是一种罕见但侵袭性强的皮肤癌。MCC通常累及真皮，尽管已有表皮浸润的报道，但严格局限于表皮内或原位的MCC（MCCIS）极为罕见。迄今为止描述的大多数MCCIS病例都有其他相关病变，如鳞状或基底细胞癌、光化性角化病等。在此，我们描述3例严格原位的MCC患者，无真皮成分。
我们的患者均为老年人。2个病变累及头颈部区域，1个位于手指。所有肿瘤在诊断性活检中均严格局限于表皮内，具有支持MCC诊断的组织形态学特征和免疫组化特征。2例患者进行了切除活检，未发现MCC或其他相关恶性肿瘤累及真皮。
我们的发现提高了人们对严格原位的MCC确实存在的认识，它应纳入佩吉特病或乳腺外佩吉特病、派杰样鳞状细胞癌、黑色素瘤以及其他通常在组织学上显示肿瘤细胞呈派杰样扩展的肿瘤的鉴别诊断中。考虑到迄今为止报道的病例数量有限，孤立性MCCIS的诊断不应导致对典型MCC治疗管理的改变。
