Lymphoepithelioma-Like Carcinoma of the Skin—A Rare Tumor Treated by Slow Mohs Micrographic Surgery
The slow Mohs specimen was examined by our regular dermatopathologist who reported that the tumor was seated in the dermis and had no connection with the epidermis. It was associated with an inflammatory process consisting of lymphocytes, histiocytes, and plasmocytes (Figure 2). The cells were atypical, with mitotic activity and epithelioid morphology. No vascular channels were seen. Immmunohistochemistry revealed expression of cytokeratins (MNF116, AE1/AE3) and epithelial membrane antigen (Figure 3). It was negative for CD3, CD20, CD21, ER, CD31, CD15, CD30, CD79a, CD4, and CD23. The in situ hybridization for Epstein-Barr Virus (EBV) was negative. Given these findings, a diagnosis of lymphoepithelioma-like carcinoma of the skin (LELCS) was made.
Lymphoepithelioma-like carcinoma of the skin is very rare, with less than 70 cases reported in the English literature. The first case of LELCS was reported in 1988 by Swanson and colleagues.1 The differential diagnosis includes metastatic nasopharyngeal carcinoma, Merkel cell carcinoma, Hodgkin lymphoma, and squamous cell carcinoma. The main histological features that differentiate it from the aforementioned diagnoses are the disassociation with the EBV (i.e., present in nasopharyngeal carcinomas), the absence of connections with the epidermis (present in Merkel cell carcinoma), the presence of cytokeratin markers (absent in Hodgkin lymphoma), and the fact that it is based in the subcutaneous tissues rather than the epidermis, which is crucial to diagnose a cutaneous squamous cell carcinoma.2 There is however a report of a EBV-related LELCS in Japan.3 All authors report that its formation is mainly on sun-exposed areas of the head.1–3 Perineural invasion is extremely rare. The main histo-pathological challenge is the differentiation with cutaneous metastasis of lympho-epithelial carcinomas (such as the nasopharyngeal carcinoma); such a metastasis, however, is extremely rare.4
Reports suggest a low metastatic potential with surgical excision being the preferred method of treatment.1–4 There have been cases of perineural invasion with incomplete surgical excision or distal metastasis requiring treatment with adjuvant radiotherapy with good outcome.2 There is only 1 report of primary treatment with radiotherapy but the outcome is not mentioned,5 although many authors suggest that nonresectable tumors or patients with surgical contraindications may be amenable to radiotherapy.1,2 Head and neck LELCS can also be treated by Mohs micrographic surgery to ascertain complete excision.2
To our knowledge, this is the first reported case of LELCS of the head and neck that has been treated with “slow” Mohs micrographic surgery. The patient has also undergone magnetic resonance imaging of the head and neck and computed tomography of the chest to exclude metastatic spread and to confirm the lesion as the primary malignancy. The decision-making process included discussion within a multidisciplinary team. This clinicopathological challenge emphasizes the importance of combined histological and clinical correlation of the objective findings to reach the correct diagnosis.