Germinoma

A germinoma is a type of germ cell tumor at eMedicine It may be benign or malignant.

Classification

The term germinoma most often has referred to a tumor in the brain that has a histology identical to two other tumors: dysgerminoma in the ovary and seminoma in the testis. Since 1994, MeSH has defined germinoma as "a malignant neoplasm of the germinal tissue of the gonads; mediastinum; or pineal region" and within its scope included both dysgerminoma and seminoma. Collectively, these are the seminomatous or germinomatous tumors.

Natural history

Germinomas are thought to originate from an error of development, when certain primordial germ cells fail to migrate properly.<!-- this is true of all germ cell tumors, not only germinomas --> Germinomas lack histologic differentiation, whereas nongerminomatous germ cell tumors display a variety of differentiation. Like other germ cell tumors, germinomas can undergo malignant transformation.

Histology

The tumor is uniform in appearance, consisting of large, round cells with vesicular nuclei and clear or finely granular cytoplasm that is eosinophilic.

On gross examination, the external surface is smooth and bosselated (knobby), and the interior is soft, fleshy and either cream-coloured, gray, pink or tan. Microscopic examination typically reveals uniform cells that resemble...
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