sicular nuclei, and one to three prominent nucleoli (Fig. 1.20a). The cytoplasm is sparse and poorly defined. Normal and abnormal mitoses may be numerous. Necroses may be present.
The LEC may exist in two histological forms: as a pure LEC and as a mixed form, composed of both LEC and conventional SCC; such a mixture has been observed both in primary and metastatic tumours .
The stroma in LECs is densely infiltrated by T lymphocytes; stromal inflammatory infiltration may also contain plasma cells, follicular dendritic cells and eosin-ophils.
Differential diagnosis includes malignant lymphoma, in particular diffuse large B-cell lymphoma, as well as malignant melanoma and rhabdomyosarcoma. Differentiation is achieved by the use of appropriate im-munohistochemical staining. The vast majority of LECs are positive for cytokeratin and negative for leukocyte common antigen as well as other lymphocyte antigens. Cytokeratin positivity has been reported in rare lymphomas , but leukocyte common antigen positivity in the tumour cells of LECs has not yet been reported. A negative reaction to S-100, HMB-45 and melan-A helps to differentiate LECs from malignant melanomas.
Lymphoepithelial carcinomas are more aggressive than conventional SCCs, with a higher incidence of cervical lymph node metastases, and a propensity for distant metastases, mostly to the lung, liver and bones [93, 227]. In a series of 34 patients with LECs, 76% of patients had lymph node metastases at the time of diagnosis, and 36% had distant metastases .
The LEC is a radiosensitive tumour and radiotherapy is an appropriate initial therapy for patients with LECs. Surgical treatment should be reserved for patients with persistent disease after completing radiotherapy. In those patients adjuvant chemotherapy is also recommended in an attempt to decrease the rate of distant metastases .
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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.