Flashcards in Melanocytes & Pigmentation Disorders Deck (15):
What triggers melanocyte proliferation / migration?
Steel (stem cell) factor binds c-KIT receptor on melanocytes → proliferation / migration
Which structures contain melanocytes?
Skin, hair, eye, ear, and brain
Which enzyme is most active in melanin synthesis pathway?
Describe the cascade of eumelanin production
Sun exposure damages cells → release of a-MSH (melanocyte stimulating hormone). MSH, ACTH, TSH, estrogen, and progesterone can all bind to melanocortin 1 receptor (MC1R) → release of tyrosine releasing protein 1 → eumelanin production
General term including depigmentation and hypopigmentation
Gray, slate, or blue discoloration due to increase in melanocytes
Vitiligo (cause, sxs, location, histology, associated diseases, tx)
Autoimmune inflammation → melanocyte destruction → depigmentation (milk-white; risk of sunburn).
Common around mouth, eyes, hands, and genitals. May Koebnerize.
Histology shows complete absence of melanocytes.
Associated w/ alopecia areata, hypothyroidism, and anemia (important to ask about fatigue).
Tx w/ topical steroids, narrow band UVB, grafting, and sunscreen.
Piebaldism (cause, sxs, timing, tx)
Abnormal migration of melanocyte due to autosomal dominant mutation in cKIT → midline depigmentation (milk-white) and white forelock (poliosis).
Present at birth. Ask about family history.
Tx w/ sunscreen and cosmetic blends.
Pityriasis Alba (cause, sxs, population, tx)
Inflammation → melanocyte downregulation → ill-defined hypopigmentation w/ scale. Common in children and people w/ atopic dermatitis.
Tx w/ sunscreen (decreases accentuation) and emollients
Oculocutaneous Albinism (cause, sxs, associated disease, tx)
Autosomal recessive tyrosinase defect → decreased melanin production.
White, yellow, red, or red-brown skin pigmentation.
Occular findings include pink iris, nystagmus, photophobia, and decreased acuity.
High risk of SCC.
Tx w/ sunscreen and cosmetic blends
Melasma (cause, sxs, location, tx, diagnostic)
Increased estrogen / progesterone (pregnancy or birth control) → increased melanin synthesis → ill-defined light / brown patchy hyperpigmentation.
Often affects forehead, cheeks, and chin. May be superficial or deep.
Tx w/ sunscreen, stopping OCPs, hydroquinone (topical bleaching agent for superficial skin), laser (superficial).
Diagnose w/ Wood’s Lamp (UV / blacklight)
Increased epidermal melanin (but normal numbers of melanocytes) → uniform light brown patches w/ sharp borders
Neurofibromatosis Type 1 (cause and sxs)
>6 CALMs, neurofibromas (rubbery skin nodules), axillary freckling and Lisch nodules (iris) are other markers for NF1.
Addison's Disease (cause and sxs)
Destruction of adrenal cortex → low cortisol → high ACTH / MSH → MC1R receptor on melanocytes → bronze hyperpigmentation. Malaise, fatigue, anorexia, nausea, abd pain, diarrhea, and low BP are other signs. May be generalized or localized.