Pigmentary Disorders

Pigmentary Disorders Indian Medical PG Question 1: Thyroxine binding globulin (TBG) is increased in:

• A. Pregnancy (Correct Answer)
• B. Cancer chemotherapy
• C. Nephrotic syndrome
• D. Glucocorticoid therapy

Pigmentary Disorders Explanation: ***Pregnancy*** - Estrogen levels are elevated during **pregnancy**, which leads to an increase in the synthesis of **TBG** by the liver. - Increased TBG binds more thyroid hormone, reducing free thyroid hormone levels, which then stimulates the thyroid gland to produce more. *Cancer chemotherapy* - Many **chemotherapeutic agents** can damage the liver or interfere with protein synthesis, potentially leading to a *decrease* in TBG and other plasma proteins. - Chemotherapy can also induce **hypothyroidism** directly or indirectly, which may alter thyroid hormone binding. *Nephrotic syndrome* - **Nephrotic syndrome** is characterized by significant proteinuria, where plasma proteins, including **TBG**, are lost through the kidneys in the urine. - This leads to a *decrease* in serum TBG levels, which can affect total thyroid hormone measurements but typically does not cause overt thyroid dysfunction due to compensatory mechanisms. *Glucocorticoid therapy* - **Glucocorticoids** (e.g., prednisone, dexamethasone) are known to *decrease* the hepatic synthesis of **TBG**. - This reduction in TBG can lead to lower total thyroid hormone levels without necessarily indicating thyroid gland dysfunction, as free thyroid hormone levels often remain normal.

Pigmentary Disorders Indian Medical PG Question 2: Melanocytes are present in which of the following layers of the epidermis?

• A. Stratum Corneum
• B. Stratum Granulosum
• C. Stratum Basale (Correct Answer)
• D. Stratum Lucidum

Pigmentary Disorders Explanation: ***Stratum Basale*** - Melanocytes are found in the **stratum basale** (basal layer) of the epidermis, specifically at the epidermal-dermal junction [1]. - Their primary function is to produce **melanin**, a pigment that protects the skin from UV radiation [1]. *Stratum Corneum* - This is the **outermost layer** of the epidermis, consisting of dead, flattened keratinocytes [1]. - Its main function is to provide a **protective barrier** against the environment. *Stratum Granulosum* - This layer is characterized by cells containing **keratohyalin granules**, which are involved in the process of keratinization. - Melanocytes are not typically found in this layer; it is primarily composed of **keratinocytes in various stages of differentiation**. *Stratum Lucidum* - The stratum lucidum is a **clear, thin layer** found only in thickened skin such as the palms of the hands and soles of the feet. - It is composed of flattened, dead keratinocytes and lacks melanocytes.

Pigmentary Disorders Indian Medical PG Question 3: Milk production in pregnancy is inhibited by :

• A. Low luteinizing hormone
• B. Low thyroid-stimulating hormone
• C. High estrogen (Correct Answer)
• D. Human somatomammotropin

Pigmentary Disorders Explanation: ***High estrogen*** - High levels of **estrogen** and progesterone during pregnancy inhibit milk production by blocking the action of **prolactin** on the mammary glands. - After delivery, the sudden drop in these hormones removes the inhibition, allowing prolactin to stimulate **lactogenesis**. *Low luteinizing hormone* - **Luteinizing hormone (LH)** is primarily involved in ovulation and corpus luteum formation, not directly in the inhibition of milk production. - Low LH levels would impact fertility but not have a direct inhibitory effect on lactation. *Low thyroid-stimulating hormone* - **Thyroid-stimulating hormone (TSH)** regulates thyroid function, which can indirectly affect metabolism and overall well-being. - While **hypothyroidism** can impact milk supply, low TSH itself is not a direct inhibitor of milk production. *Human somatomammotropin* - **Human placental lactogen (HPL)**, also known as human chorion somatomammotropin, is produced by the placenta. - It promotes mammary gland development and has weak lactogenic properties but does not inhibit milk production.

Pigmentary Disorders Indian Medical PG Question 4: A young girl presents with leukotrichia and lesions as shown in the image. What is the most likely diagnosis?

• A. Segmental vitiligo (Correct Answer)
• B. Piebaldism
• C. Focal vitiligo
• D. Nevus depigmentosus

Pigmentary Disorders Explanation: ***Segmental vitiligo*** - Segmental vitiligo characteristically presents as unilateral, **dermatomal** or **quasi-dermatomal depigmentation** with sharply demarcated borders, often including overlying **leukotrichia** (white hairs) in the affected area, as seen in the image. - This form typically has an early onset, rapid progression followed by stabilization, and can be more resistant to conventional treatments than non-segmental vitiligo. *Piebaldism* - Piebaldism is a **congenital leukoderma** characterized by a **white forelock** and symmetrically distributed depigmented patches, primarily on the trunk and extremities, which are usually stable in size and present from birth. - Unlike the progressive nature and unilateral pattern seen in the image, piebaldism is a genetic condition without new lesion development or the characteristic dermatomal distribution. *Focal vitiligo* - Focal vitiligo refers to one or a few localized depigmented macules that do not have a segmental pattern and are not distributed along a specific dermatome. - While it involves localized depigmentation, the clear **segmental distribution** and presence of **leukotrichia** in the image are more indicative of segmental vitiligo. *Nevus depigmentosus* - Nevus depigmentosus is a congenital, **stable hypopigmented lesion** that typically appears as a solitary patch or macule, without subsequent growth or change in size over time. - The lesions shown in the image appear to be multiple and follow a distinct pattern that is not typical of a stable, solitary nevus.

Pigmentary Disorders Indian Medical PG Question 5: What is the classification of intelligence corresponding to an IQ score of 90-109?

• A. Below average
• B. Average (Correct Answer)
• C. Slightly below average
• D. Above average

Pigmentary Disorders Explanation: ***Average*** - An **IQ score** range of **90-109** is traditionally classified as **Average** intelligence. - This range represents the **mean** and surrounding **standard deviation** of IQ scores in the general population. *Below average* - This classification usually corresponds to IQ scores in the range of **70-79** or **80-89**, depending on the specific scale. - It does not represent the central tendency of the population's intelligence. *Slightly below average* - This category typically corresponds to IQ scores in the range of **80-89**. - It falls just below the average range but is not as low as the "below average" classification. *Above average* - This classification is typically assigned to IQ scores that are in the range of **110-119** or higher. - It signifies cognitive abilities that are greater than the majority of the population.

Pigmentary Disorders Flashcard 1 of 5

Question: _____dermal melasma -appears slightly grey or bluish on gross examination and shows less color contrast with Wood s lamp

Answer:

Pigmentary Disorders Flashcard 2 of 5

Question: Naevus of Ota is an extensive, _____, patchy, dermal melanocytosis

Answer: bluish (colour)

Pigmentary Disorders Flashcard 3 of 5

Question: First-line treatment for freckles is the use of a _____.

Answer: broad-spectrum sunscreen

Pigmentary Disorders Flashcard 4 of 5

Question: Albinism is associated with a _____ melanocyte count with decreased melanin production

Answer: normal

Pigmentary Disorders Flashcard 5 of 5

Question: _____ is a mask-like hyperpigmentation of the cheeks associated with pregnancy and OCPs

Answer: Chloasma