Integument (Part 2: Clinical Correlations) BIO11.01 PDF

Integument (Part 2: Clinical Correlations) BIO11.01 Human Biology, Health and Disease, Lecture First Semester 2024-2025 September 12, 2024 Skin Lesions Blisters (Vesicles vs. Bullae) Pustule Papule and Nodule Macule and Patch Blisters Recall: Discussi...

Integument (Part 2: Clinical Correlations) BIO11.01 Human Biology, Health and Disease, Lecture First Semester 2024-2025 September 12, 2024 Skin Lesions Blisters (Vesicles vs. Bullae) Pustule Papule and Nodule Macule and Patch Blisters Recall: Discussion on burns. What type of burn would manifest with blisters? Blisters appear as fluid-filled skin lesions. These may be classified further based on their size. Vesicle (5 mm or less in diameter) Bulla (greater than 5 mm in diameter) Chickenpox is an infection associated with the varicella zoster virus (VZV). The typical lesion associated with chickenpox are vesicles distributed across the body. Note the fluid-filled vesicles on chickenpox. To prevent any bacterial infection, it is advisable not to manipulate or rupture the vesicles. Bullae are large fluid filled lesions that are larger than vesicles. The bullae seen in these images are associated with a burn injury. In some cases of ruptured blisters, it would be prudent to keep the overlying skin as this would act as a natural dressing to protect the skin underneath. Pustules Pustules appear as skin lesions filled with pus (a yellow fluid filled with dead white blood cells, bacteria, serum and tissue debris). Pustules are associated with bacterial infections and the body’s attempt to control the infection. (e.g., acne as seen in the picture). Acne (pimples) can result from the infection of hair follicles leading to the formation of pustules. Papules and Nodules Papules and nodules are raised, elevated palpable lesions that are described to be “dome-like.” Unlike vesicles and pustules, these lesions appear solid and does not contain any fluid. Papule (5 mm or less in diameter) Nodule (Greater than 5 mm) Some cases of acne can appear as papules instead of pustules. Macule and Patches In contrast to blisters and pustules, macules and patches appear as circumscribed, flat lesions that have well-defined margins. These lesions are usually distinguished from adjacent skin through color. Macules – 5 mm or less in diameter Patch – Greater than 5 mm Depending on their size, birthmarks could be classified as either macules or papules. Many birthmarks arise due to the activity of melanocytes. In some cases it might be due to proliferating blood vessels. Flat nevi (moles) can also appear as macules. The region is distinguished by its increased melanin content compared to adjacent skin. Some rashes are described to be ”maculopapular” due to the presence of both macules and papules. The rash seen here can is associated with a measles (rubeola) infection. Initially appearing on the head, these rashes are noted to spread inferiorly. Child presenting with measles (rubeola). Some rashes are described to be ”maculopapular” due to the presence of both macules and papules on the skin. Wound Healing and Scars (pp. 166-167) Recall: Contractures that may arise from extensive burns. Traumatic injury to the skin (e.g., abrasions) trigger a series of events that promote wound healing. Controlling possible infections (e.g., migration of white blood cells, formation of a blood clot and a scab) Extensive growth of epithelial cells within the epidermis. Deposition of collagen fibers by the fibroblasts. The process of scar formation is known as fibrosis. Depending on the extent of an injury, scar tissue may appear raised or palpable. Wound Healing - Depending on the depth of injury, dermis can also be affected by traumatic injury and and may involve blood vessel rupture. A blood clot will form above the injury providing a barrier against infection which then forms a “scab.” As the skin heals underneath the scab, it will eventually form a scar. Scars form when there are deeper injuries to the skin (e.g., damage involving the dermis). As collagen fibers accumulate to heal the site of injury, this may lead to the formation of an elevated scar. Some individuals are predisposed to form keloids wherein the fibroblasts in the dermis produce excess collagen making the scar markedly elevated. In these cases, the scar tissue extends into the normal surrounding tissue. Keloid that has likely arisen from an ear piercing. Mpox (Monkeypox) A viral infection , mpox is prevalent in some parts of the African continent. Classified as a zoonotic infection since the virus can be transmitted from animals to humans. Animal hosts are noted to occupy niches in rainforests. Two lineages of the mpox virus have been identified. Clade I – Congo basin (central African Clade) – more severe Clade II – former West African Clade Mpox (Monkeypox) Among humans, the disease can be spread through contact with body fluids, respiratory droplets, fomites (contaminated objects). Physical contact or extended periods of time may lead to infection. Given this, one can say that this infection may occur with sexual contact. (Some references would mention that mpox is not an sexually transmitted infection). Signs and Symptoms The incubation period of mpox lasts 5-21 days. (Duration between infection and the onset of signs and symptoms. Fever (1-3 days) Headaches, lymphadenopathy, muscle pains, generalized body weakness Lesions may initially manifest as macules, papules, vesicles, then followed by pustules and scabs (crusting). Thank you!