MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

SECTION 1. ORGAN. ORGAN SYSTEM. ORGANISM

TUMORS

CLASSIFICATION OF TUMORS

4.TUMORS OF MELANIN-PRODUCING TISSUE

Tumors of this group develop from Cells of neurogenic origin (melanocytes) that produce melanin and melatonin. Melanocytes can give rise to true tumors—melanomas, as well as tumor-like lesions—nevi.

Nevi are most commonly observed in the facial and truncal regions as elevations above the Skin surface.

Melanoma is one of the most malignant tumors. It occurs primarily in individuals aged 30 to 50 years, with its predominant localization being the skin of the back, HEAD, neck, and torso in men, while in women it is more frequently found on the thighs and lower legs. Less commonly, melanoma develops in the pigmented layer of the eye, the Meninges, or the Adrenal Glands. It appears as a patch or a nodule of various shades of black. Melanomas arise either from pre-existing nevi (more frequently) or without prior changes.

Melanoma grows in all directions, tends to recur following surgical removal, and exhibits early, widespread, predominantly hematogenous metastasis. Self-Treatment—often due to cosmetic concerns—or biopsy tends to exacerbate the aggressive Properties of the tumor.

Tumors of The Nervous system and meninges, as well as tumors of the hematopoietic system, are described in subsequent sections.

Teratomas are a special type of tumors that originate from Germ Cells.