Pathology of the Dermis II Flashcards
(25 cards)
what is Vitiligo?
Partial or complete loss of melanocytes within the epidermis causing flat, well-demarcated macules and patches of pigment loss, ranging in size occurring mainly on the hands, wrists, axillae, perioral, periorbital, and anogenital skin
** theories point to autoimmune destruction
what is albanism?
Genetic condition characterized by absent melanin production due to disruption in the tyrosine catabolism pathway, particularly tyrosinase deficiency causing complete or partial lack of pigment in skin, hair, and eyes
what are Freckles (Ephelides)?
Small (1–several mm), tan-red or light brown macules that appear after sun exposure caused by an increase in melanin production in the basal keratinocytes
what are Melanocytic Nevi (Pigmented Nevus, Mole)?
Benign neoplasms of melanocytes that can be congenital or acquired often caused by mutations in BRAF or RAS signaling pathways
*induces melanocytic proliferation followed by a permanent growth arrest mediated by the accumulation of p16/INK4a, a potent inhibitor of several cyclin-dependent kinases, including CDK4 and CDK6
what are the subtypes of Melanocytic Nevi?
- Junctional Nevus:
- Location: Dermal-epidermal junction.
- Appearance: Flat and symmetric. - Compound Nevus:
- Location: Extends into the dermis.
- Appearance: Raised and dome-shaped. - Dermal Nevus:
- Location: Confined to the dermis.
- Appearance: Elevated and sometimes nodular.
what is maturation in Melanocytic Nevi?
feature of benign nevi in which the most superficial nevus cells are immature, larger and melanin producing, and the deeper cells are mature, smaller, fusiform and do not produce pigment
what are Dysplastic Nevi?
Atypical moles that can be isolated or part of dysplastic nevus syndrome, increasing melanoma risk, can occur on both sun-exposed and non-exposed skin and there is a higher risk of malignancy if part of dysplastic nevus syndrome
what are the microscopic findings of Dysplastic Nevi?
- Architectural abnormalities: Larger nests that fuse together
- Melanocytic atypia: Irregular, hyperchromatic nuclei
- Lymphocytic infiltrate: In the upper dermis
- Fibrosis: Linear dermal fibrosis around rete ridges
what is Malignant Melanoma?
highly aggressive cancer that originates from melanocytes, primarily affects the skin, but can also appear in the oral and anogenital mucosa, esophagus, meninges, and the eye and often develops in sun-exposed areas and is more prevalent in lightly pigmented individuals
***Acral melanoma (affecting the skin of palms, soles, and nails) is more common in darker-skinned individuals
what are the growth phases of Malignant Melanoma?
Radial Growth Phase:
- Melanoma cells grow horizontally along the epidermis and superficial dermis.
- No metastatic potential during this phase.
Vertical Growth Phase:
- Cells begin to grow vertically into the deeper dermis.
- associated with no maturation of cells and a higher risk of metastasis.
- key indicator of aggressiveness
what are the microscopic features of Malignant Melanoma?
- Large, irregular nuclei with clumped chromatin and prominent red nucleoli
- Nests of tumor cells found in the epidermis during the radial phase and in the dermis during the vertical phase
what is measured to predict the probability of metastasis and overall prognosis of Melanomas?
- Breslow Thickness: depth of invasion of melanoma from the top layer of the skin (deep=bad)
- Mitosis Rate: rate of cell division; (higher rates=aggressive behavior)
- Ulceration: presence of ulceration on the surface = worse prognosis
- Regression: areas where melanoma cells are being destroyed by the immune response
- Tumor-Infiltrating Lymphocytes (TILs): the brisker the lymphocyte response, the better the prognosis.
what is Seborrheic Keratosis?
common benign tumor in middle-aged and older individuals occurring mainly on the trunk, but also on extremities, head, and neck
what are the clinical features of Seborrheic Keratosis?
- Round, flat, coin-like plaques
- Color ranges from tan to dark brown
- Granular surface giving the impression of being “stuck on.”
what are the microscopic features of Seborrheic Keratosis?
- Exophytic and well-demarcated.
- Composed of basal epidermal cells with melanin pigmentation and hyperkeratosis in the form of keratin-filled cysts (horn cysts).
- Can appear in large numbers as part of paraneoplastic syndrome (Leser-Trélat sign), often linked to adenocarcinoma of the stomach
what are Fibroepithelial Polyps?
- common benign skin growth, also called Acrochordon, squamous papilloma or skin tag
- Fibrovascular cores covered by benign squamous epithelium
- found on neck, trunk, face, and intertriginous areas (e.g., underarms).
- appear soft, flesh-colored, bag-like and attached to the skin by a slender stalk
what are Epithelial or Follicular Inclusion Cysts (Wen)?
Common dermal or subcutaneous cysts caused by cystic expansion of the epidermis, filled with keratin and lipid debris found as firm, moveable nodules under the skin
**Can cause intense inflammation if ruptured
what is Actinic Keratosis (AK)?
Premalignant lesion associated with chronic sun exposure that induces DNA damage involving p53 mutations that commonly occurs on face, arms, hands, and lips (especially actinic cheilitis)
- 0.1% to 2.6% progress to SCC (Squamous Cell Carcinoma) per year
- Lesions are <1 cm, tan-brown, red, or skin-colored with a rough surface
what are the microscopic features of Actinic Keratosis (AK)??
- Parakeratosis: Retained nuclei in the stratum corneum, indicating abnormal maturation
- Cytologic Atypia: Abnormal cells in the lower epidermal layers with hypertrophic or atrophic changes
- Elastosis: Blue-gray elastic fibers in the upper dermis from sun damage
what is Squamous Cell Carcinoma (SCC)?
Second most common skin cancer in sun-exposed areas, mainly in older adults where exposure causes mutations in p53, RAS, and Notch receptors.
***Additional Risk Factors: Industrial carcinogens, chronic ulcers, arsenicals, ionizing radiation, and tobacco
what are the clinical features of Squamous Cell Carcinoma (SCC)?
- In Situ Carcinoma: Sharply defined, red, scaling plaques but malignant cells have not invaded beyond the basement membrane
- Invasive Carcinoma: Nodular lesions and ulceration that extend beyond the epidermis
- Oral Mucosa Manifestation: Appears as Leukoplakia—a white thickening
- Metastasis Risk: Less than 1% at the time of diagnosis
what are the microscopic features of Squamous Cell Carcinoma (SCC)?
- atypical enlarged hyperchromatic cells at all epidermal levels.
- In Situ: Confined to the epidermis
- Invasive: Invades through the basement membrane into the dermis
what is Basal Cell Carcinoma (BCC)?
Most common skin cancer in sun-exposed areas, particularly in lightly pigmented individuals with slowly growing pearly papules with telangiectasia (dilated blood vessels)
**Metastasis: Rare, but can deeply invade tissues and bone (rodent ulcers)
what are the molecular hallmarks of Basal Cell Carcinoma (BCC)?
- Mutations in PTCH1: Tumor suppressor gene regulating Hedgehog signaling.
- Gorlin Syndrome: Associated with familial BCC and PTCH1 defects.
- p53 Mutations: Contribute to tumor development.
