W11 _6 Ian Melanocytic Tumors, Teratoma

Melanocytic tumors; teratomas Workshop 11

Melanocytic tumors • Melanocytic tumors originate in melanocytic cells – These cells are synthesizing melanic pigment

• There are 2 types of melanocytic tumors: – benign: nevi – malignant: malignant melanomas

Nevi • • •

They are cutaneous benign melanocyte tumors They have origin in the melanocytes from basal layer of epidermis Microscopically, nevi could be  epidermal or jonctional  compound  dermal

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Compound nevus • Nests of nevus cells in epidermis and subjacent dermis • The nevus cells have uniform, round nuclei, without mitotic activity • By passing from epidermis toward dermis the nevus cells become smaller and elongated – phenomena called maturation

Cutaneous malignant melanoma • • •

It is a malignant tumor with origin in the epidermal melanocytes Microscopy: 2 types of growing – Horizontal or radial growth superficial malignant melanoma – Vertical growth  nodular malignant melanoma Microscopically, there are two histological types:  Round or poligonal cells  Epitheloid malignant melanoma  Fusiforme cells  Sarcomatoid malignant melanoma

Malignant melanoma  The tumor has an infiltrative character in the subjacent dermis  The tumor is composed from sheets of atypical, spindle melanocytes with elongated, hyperchromatic and pleomorphic nuclei with atypical mitoses.  The stroma is reduced and contains melanophages (macrophages with melanic pigment)  The tumor contains necrotic areas.

Teratomas •

Teratomas are complex tumors, consisting of multiple tissue types, with origin in germinal multipotent cells at the level of one or all 3 embryonal layers (ectodermal, mesodermal and endodermal layers) • Classification (depending on the tissue type): – After location: mid line or paramedian line of the body: (a) the median line: the sacro-coccigian, mediastinal, retroperitoneal, or cervical region; (b) paramedian zones: ovary, testis.

– After gross appearances: • Cystic tumors • Solid tumors • Mixt tumors: solid tumor with mycrocystic structures

– After evolution of teratomas there are 2 main types of tumors: (a) benign • usually, cystic lesion  mature tissues; e.g. Ovary mature dermoyd cyst • rarely, solid tumor mature tissues; e.g. testicular mature solid teratoma

(b) malignant  immature solid tumors;

Mature micro cystic/solid testicular teratoma •

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The tumor has origin in multipotent germinal cells (origin in the 3 embryonic layers) Is composed from multiple normal tissues: – Sheets of hyaline cartilage – Fibrous tissue – Microcystic spaces lined by respiratory epithelium

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The tissues are disorderly disposed and normaly, they are not located in this place

Mature cystic ovarian teratoma •

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The tumor has origin in the germinal multipotent cells (with origin in the 3 embryonic layers) Histological section through the cyst wall  numerous mature tissues:  Sheets of hyaline cartilage  Fibrous tissue  Muscular cells  Neural tissue  Respiratory epithelium  Adipose tissue  Microcystic spaces lined by a mucosecretory glandular epithelium The tissues are chaotically disposed and have no relation with the place where they develop.