Podcast
Questions and Answers
What is the genetic basis for generalised hypopigmentation in albinism?
What is the genetic basis for generalised hypopigmentation in albinism?
What are common features of oculocutaneous albinism?
What are common features of oculocutaneous albinism?
Which condition is characterized by localized loss of pigmentation in the skin?
Which condition is characterized by localized loss of pigmentation in the skin?
What is a common risk associated with chronic sun exposure in individuals with albinism?
What is a common risk associated with chronic sun exposure in individuals with albinism?
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What distinguishes vitiligo from leucoderma?
What distinguishes vitiligo from leucoderma?
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What is the role of tyrosinase in melanocyte cells?
What is the role of tyrosinase in melanocyte cells?
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Which of the following conditions is associated with generalised hyperpigmentation?
Which of the following conditions is associated with generalised hyperpigmentation?
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What is the DOPA reaction used to identify?
What is the DOPA reaction used to identify?
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Café-au-lait spots are commonly seen in which condition?
Café-au-lait spots are commonly seen in which condition?
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Which entity is indicative of focal hyperpigmentation around the mouth?
Which entity is indicative of focal hyperpigmentation around the mouth?
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Rain-drop pigmentation is associated with which type of poisoning?
Rain-drop pigmentation is associated with which type of poisoning?
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What typically characterizes lentigo?
What typically characterizes lentigo?
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Melanin is NOT normally found in which of the following locations?
Melanin is NOT normally found in which of the following locations?
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Study Notes
Endogenous Pigments
- Endogenous pigments are normal cellular components or accumulated substances (melanin, alkaptonuria products, haemoprotein-derived pigments, lipofuscin)
- Melanin is a brown-black pigment found in hair, skin, mucosa (in places), choroid, meninges, and adrenal medulla.
- Synthesised in melanocytes and dendritic cells (basal epidermis).
- Stored in cytoplasmic granules of melanophores (underlying dermis).
- Melanocytes contain tyrosinase, for melanin synthesis from tyrosine.
- Tyrosinase inactivity may result in no visible melanin.
- DOPA reaction (incubating tissue in DOPA) detects tyrosinase presence (dark pigment) - distinguishes amelanotic melanoma.
Melanism Disorders
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Generalised Hyperpigmentation:
- Addison's disease: Skin (light-exposed areas) and buccal mucosa hyperpigmentation.
- Chloasma (pregnancy): Face, nipples, genitalia hyperpigmentation (due to oestrogen). Similar appearance in oral contraceptive users.
- Chronic arsenical poisoning: "Rain-drop" skin pigmentation.
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Focal Hyperpigmentation:
- Café-au-lait spots: Pigmented patches in neurofibromatosis and Albright's syndrome.
- Peutz-Jeghers syndrome: Peri-oral pigmentation.
- Melanosis coli: Pigmented colon mucosa.
- Melanotic tumours: Benign (pigmented naevi), malignant (melanoma); increased melanogenesis.
- Lentigo: Pre-malignant condition; hyperpigmentation on hands, face, neck, arms.
- Dermatopathic lymphadenitis: Melanin deposition in lymph node macrophages.
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Generalised Hypopigmentation:
- Albinism: Tyrosinase deficiency; no pigment in skin, blond hair, poor vision, severe photophobia, high sunlight sensitivity; pre-cancerous lesions and skin cancers possible with chronic sun exposure.
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Localised Hypopigmentation:
- Leucoderma: Autoimmune loss of skin pigmentation.
- Vitiligo: Common local skin hypopigmentation (possible familial tendency).
- Acquired focal hypopigmentation: Due to various causes.
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Description
Explore the fascinating world of endogenous pigments, including melanin production and its role in various skin conditions. This quiz covers melanin synthesis, disorders related to hyperpigmentation, and the impact of conditions like Addison's disease and chloasma. Test your knowledge on these crucial biological pigments and their implications.
