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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