ABSTRACT
Carcinoma of unknown primary (CUP) in a single site accounts for about one-third of patients with CUP, and possibly represents a better prognosis than common forms. Differential diagnosis is particularly important, notably with a primary malignant tumor, and immunohistochemistry (IHC) can be especially helpful here. This entity justifies more extensive investigations (including positron emission tomography) than in disseminated forms, and such an approach may have an influence on the subsequent therapy for the patients. Local treatments (surgery, radiotherapy, etc.) are of particular importance when the metastasis is located in a single site, and chemotherapy (and/or hormone therapy for women in the event of positive hormonal receptors) may be considered even if its efficacy has not been fully evaluated in the literature.
