Melanocytes - Holland Flashcards
From where are melanocytes derived?
What do their dendrites do?
Where are they located?
From neural crest (has to migrate in).
Dendrites for melanin transfer.
Located in the stratum basale.
Explain the basis behind variable skin color (eg why caucasian skin is lighter than african)
Has nothing to do with melanocyte number or size; purely related to size and number of the melanosomes they produce.
How might you distinguish hypopigmentation from depigmentation?
Use a Wood’s lamp.
Tuberous Sclerosis
Etiology?
Pathophysiology?
Skin findings?
Tuberous Sclerosis
AutDom (usually spontaneous) mutations in TSC1 (hamartin) / TSC2 (tuberin).
Forms numerous non-malignant tumors in many tissues.
Ash leaf macules, cafe-au-lait spots, shagreen patches, ungual fibromas, angiofibromas & fibrous plaque (adenoma sebaceum?)
Vitiligo
Etiology?
Pathophysiology?
Skin findings?
Can it be treated?
Vitiligo
T-cell autoimmunity against melanocytes.
Progressive loss of melanocytes, acquired at any age.
Depigmented patches, poliosis.
Give steroids, UV treatment.
Oculocutaneous Albinism
Etiology?
Pathophysiology?
Skin findings?
Can it be treated?
Oculocutaneous Albinism
Many possible genetic disorders impairing melanin production (eg Tyrosinase)
Impaired melanin production, resulting in depigmentation.
Complete lack of pigment. Pale hair, “red” eyes.
Nope. Enjoy your cancer.
Why is OC albinism associated with visual loss?
Melanocytes are present in the eye and are important to its function (nevi can be found behind the retina)
What is the proper name for freckles? What are they?
Ephelides. Hyperpigmented spots (macules) found in sun-exposed areas.
What conditions are associated with cafe au lait spots?
Tuberous Sclerosis, Neurofibromatosis (McCune-Albright)
(need to see several for this suspicion)
Neurofibromatosis 1
Etiology?
Pathophysiology?
Skin findings?
Can it be treated?
VON RECKLINGHAUSEN’S DISEASE
AutDom mutation in neurofibromin.
RAS overactivation >> fibromas.
Cafe-au-lait macules, axillary/inguinal freckling, neurofibromas (late in life; sometimes plexiform).
*shrug*
What are solar lentigines?
(singular: lentigo)
Macule from UV radiation, seen in the sun-exposed parts of the elderly.
What does dermal melanocytosis look like?
A bluish discoloration usually in the lumbrosacral region (fades over time, AKA “Mongolian spot”)
Recall the 3 subtypes of melanocytic nevi.
What is significant about giant congenital nevi?
Junctional (epidermis), Compound (epidermis-dermis), Intradermal (dermis).
Giant congenital nevi have a higher risk of melanoma transformation.
