Pathology Notes

Tricholemmoma Updated: 07/01/2023 © Jun Wang, MD, PhD General features AKA trichilemmoma Benign Derived from the outer root sheath of hair follicle May be associated with other neoplasms, most commonly nevus sebaceous of Jadassohn Cowden syndrome Multiple trichilemmomas Multiple hamartomas in skin, oral mucosa, breast, thyroid and intestines Malignancies at these sites Clinical features Papules Pathological features Lobularor plate-like growth of pale pink, glassy cells Palisading at periphery Thickened basement membrane Occasional central keratinization Management Excision Back to skin tumors Back to skin pathology Back to contents

Trichoepithelioma Updated: 07/01/2023 © Jun Wang, MD, PhD General features Benign Often in children, may be familial ( 9p21 ) May be CYLD (16q12-q13) associated If multiple, may be autosomal dominant May recur if partially removed, or familial form Clinical features Slow growth, rarely transformed to malignancy Papules or nodules Pathological features Basaloid cells (like cylindroma) Primitive hair follicle with peripheral cell palisading Management Excision Back to skin tumors Back to skin pathology Back to contents

Syringoma Updated: 03/28/2019 © Jun Wang, MD, PhD General features Most commonly seen in lower eyelids of women Probably derive from sweat duct ridge Clinical features Multiple, small, yellow papule Pathological features Small tadpole shaped ducts in a sclerotic stroma Management Electrosurgery Laser Back to skin tumors Back to skin pathology Back to contents

Sebaceous adenoma   Updated: 02/15/2021 © Jun Wang, MD, PhD General features Associated with Muir-Torre Syndrome Muir-Torre syndrome Combination of neoplasms of the skin (usually sebaceous adenoma, sebaceous epithelioma, or sebaceous carcinoma but also keratoacanthoma) and a visceral malignancy (usually colorectal, endometrial, small intestine, and urothelial)   Commonly autosomal dominant Considered a subtype of Lynch syndrome Associated with DNA mismatch repair gene (MMR), which leads to microsatellite instability, most commonly with MSH2 Clinical signs suggestive of Muir-Torre syndrome Family or personal history of Lynch-related cancers One or more sebaceous tumors Age younger than 60 years at first presentation of sebaceous tumors Clinical features Papule/nodule on face/scalp Pathological features Hyperplasia of sebaceous lobules Lobulated growth of generative cells (dark) and sebaceous cells (light) Cytoplasmic lipid vacuoles Managemen

Squamous cell carcinoma of skin   Updated: 03/16/2021 © Jun Wang, MD, PhD General features Second most common skin cancer, after basal cell carcinoma Commonly older population, men Incidence associated with latitude Higher risk in light skinned population Usually NOT fatal Excellent prognosis Metastases uncommon Risk factors Exposure to natural and artificial ultraviolet light Exposure to arsenic, tars and oils, ionizing radiations Tobacco and betel nut chewing ( oral cavity SCC ) Immunosuppression HPV: Especially for SCC of anogenital or periungual sites; HPV 5/8 for patients with epidermodysplasia verruciformis Certain skin disorders: light skin, actinic keratosis, xeroderma pigmentosum, epidermodysplasia verruciformis, albinism Key pathogenesis UV UVB: most carcinogenic, absorbed by DNA DNA damage and p53 mutation Actinic keratosis Also called solar keratosis, senile keratosis Precancerous lesion on sun-exposed areas May develop into squ