[Histology of bone metastases (technical aspects, searching for a primary)]

The histologic diagnosis of bone metastasis is often easy, based on tumor morphologic features on routine examination. The determination of the primary tumor is facilitated by ancillary techniques such as histochemical stainings and immunohistochemistry: it is possible, in about 65% of cases, with clinical correlation. Additional immunohistochemistry or molecular analyses are becoming more useful in various tumors (breast, lung, melanoma…) to give targeted therapy. From a technical point of view, bone is characterised by its difficulty to be sampled (with frequent crushing artifacts) and the necessity to decalcify samples with increase time of technique and frequent loss of nuclear markers antigenicity and difficulties in molecular analyses.