Skin diseases and allergic reactions 

Skin lightening, also known as skin bleaching, is the use of cosmetic or medicinal products to reduce the amount of melanin in the skin in order to obtain a lighter complexion or reduce areas of hyperpigmentation. While certain skin-lightening agents are appropriately prescribed for medical conditions such as melasma and post-inflammatory hyperpigmentation, the unsupervised or prolonged use of these products for cosmetic purposes can lead to serious local and systemic complications.

Dermoid cyst is a congenital benign cystic lesion that develops due to sequestration of ectodermal tissue during embryonic development. It contains skin structures such as hair follicles, sebaceous glands, and sweat glands and may also contain hair and sebaceous material.

Trichilemmal cyst, also known as a pilar cyst, is a benign, slow-growing cyst arising from the outer root sheath of the hair follicle. It most commonly occurs on the scalp, where it accounts for the majority of scalp cysts. Unlike epidermoid cysts, trichilemmal cysts usually lack a central punctum and contain dense keratin. They often occur in multiple family members due to an inherited predisposition.

Epidermoid cyst (previously called an epidermal inclusion cyst or sebaceous cyst) is a common benign, slow-growing cystic lesion that develops from the epidermis. It is lined by stratified squamous epithelium and contains keratinous material rather than sebum. Epidermoid cysts may occur anywhere on the body but are most common on the face, neck, trunk, and back.

Infantile haemangioma is the most common benign vascular tumor of infancy, arising from abnormal proliferation of endothelial cells. It typically appears during the first few weeks of life, undergoes a period of rapid growth during infancy, and then gradually regresses over several years.