Immunohistochemical markers for recognition tissue of origin in metastatic cancers

الملخص EN

Metastatic cancer can be the first manifestation in patient with malignancy, where the primary cancer's source is undetermined.

The immunohistochemistry (IHC) is required in such cases, by using certain panels of immune-stains, to identify the cancer type or tissue of origin to determine the specific therapy in the oncology unit.

The aim of the study is to apply different IHC panels to tissue sections of cases suspected to be metastatic cancers of undetermined origin by histopathological examination (H.P) to predict different tissue of origin and to clarify certain criteria of metastatic cancers including the type and main primary and secondary sites.

After reviewing 1316 cancer cases diagnosed by H.P from August 2009 to December 2012, a total of 175 cases were diagnosed as metastatic cancers of undetermined origin.

Panels of IHC markers were used to identify the type and tissue of origin.

Among the 1,316 reviewed malignant cases, 175 cases were diagnosed as secondary by histology.

The IHC analysis showed that only 162 of them were secondary cancers (12.3%).

The commonest site of secondary at time of diagnosis was the abdominal cavity followed by the bone, lymph nodes, liver, lung, pleura and ovary.

The IHC revealed that carcinoma (62%) was the commonest type of metastasis followed by undifferentiated malignancy (16%), lymphoma, sarcoma, and neuroendocrine tumors.

The commonest primary malignant site was the GIT (37%), metastasized to the abdomen cavity, bone, lymph nodes, liver and ovary.

In conclusion the use of IHC is an important ancillary test to approach the diagnosis of secondary tumors and to identify their type and tissue of origin.