Microscopical synopsis

 microcystic pattern

• interconnecting cords and ribbons of tumor cells are surrounded by abundant myxoid stroma
• intracellular vacuoles
• vesicular nuclei with punctate nucleoli
• often coexists with other architectural patterns

 myxomatous pattern

• neoplastic stellate cells
• spindle cells
• epithelioid cells
• abundant myxoid stroma
• many of these cells are pluripotential and can form skeletal muscle, cartilage, and bone (such areas should not be confused with teratoma)

 endodermal sinus pattern

• Schiller-Duvall body: central vessel surrounded by tumor cells in a cystic space often lined by flattened tumor cells

 hepatoid pattern (20%)

• sheets of polygonal cells with abundant eosinophilic cytoplasm
• hyaline globules
• bile canaliculi

 solid pattern

• sheets of uniform tumor cells with clear or pale pink cytoplasm
• differential diagnosis: seminoma (it lacks the fibrous septa with lymphoid infiltrate seen in seminoma)

Cytogenetics

 deletion of chromosome 1p36 (#9162192#)
 deletion of distal regions of chromosome 6q

Molecular biology

 LOH of 6q (72%) (#11753688#)
 LOH of 1p (45%) (#11753688#)