Systemic Diseases and Skin MCQs

During development of the epidermis, first layer to form is S. Basale and subsequently, layers form from below upwards. The principal function of epidermis is constant replacement of the stratum corneum which is being continuously shed and replaced Total epidermal cell turnover time is 52-75 days. Reference: Rooks textbook of dermatology 9th edition, chapter 2, page 2

The epidermis is a keratinized, stratified, squamous epithelium and the hallmark filaments are the keratin intermediate filaments. Melanocytes originate from neural crest and are present in stratum basale. Merkel cells originate from ectoderm and are present in stratum basale. Langerhans cells are dendritic cells which originate from bone marrow and function as antigen presenting cells. They are present in stratum spinosum Reference: Rooks textbook of dermatology 9th edition, chapter 2, page 1

Present in Stratum Germinativum/ Basal Cell Layer Contains Melanocytes which produce melanin Sun exposure increase melanin production to prevent damage from UV rays (sun tanning) Reference: Rooks textbook of dermatology 9th edition, chapter 2, page 17

Skin biopsy of a nevus anemicus lesion will show normal findings, including an uninvolved epidermis with normal melanocyte number and distribution. Reference: Rooks textbook of Dermatology, 9 th edition, chapter 70, page 5

Most collagen fibrils are comprised of several collagen types and are called heterotypic Collagen fibrils are made of collagens I and III in skin. Type 1 is most abundant collagen in skin (80%) and second most common is type 3 (10. Type 2 collagen is not found in skin and is unique to cartilage. The ratio between type I and Ill collagen is 8:1. The rating of Type 1 to Type 3 collagen in the adult human skin is 8:1 and increases with age Reference: Rooks textbook of dermatology 9 th edition, chapter 2, page 27

Epidermis, keratinocytes, merkel cells originate from ectoderm. Langerhans cells and dermis originates from mesoderm. Skin weight is 4-5 kg and makes 15% of total body weight. Most collagen fibrils are comprised of several collagen types and are called heterotypic. Collagen fibrils are made of collagens I and III in skin. Type 1 is most abundant collagen in skin (80%) and second most common is type 3 . Type 2 collagen is not found in skin and is unique to cartilage. The ratio between type I and Ill collagen is 8:1 and increased along with increase in age. Reference: Rooks textbook of dermatology 9 th edition, chapter 2, page 1

Acanthosis nigricans is not pre malignant: It is a paraneoplastic condition associated with gastric adenocarcinoma. Pre-malignant skin lesions: Cutaneous horns, Keratoacanthoma, 'Bowen's disease, Actinic keratoses, Arsenical keratoses, Leukoplakia Reference: Rooks textbook of dermatology, chapter 142, Chapter 142, page 1

Associated Features of Acanthosis Nigricans Obesity, Diabetes mellitus, Metabolic syndrome Hyperandrogenism, Cushing syndrome polycystic ovary syndrome (PCOS) HAIR -AN syndrome - HAIR-AN-a syndrome of hyperandrogenism(HA), insulin resistance (IR) and acanthosis nigricans (AN)-is a specific and rare subphenotype of the polycystic ovary syndrome (PCOS) characterised by the presence of severe insulin resistance. Drugs : Nicotinic acid,, Corticosteroids, Oral contraceptives Gastric adenocarcinoma Reference: Rooks textbook of dermatology 9 th edition, chapter 89, page 3