- Epidermoid cysts occur on face, neck, trunk or anywhere where there is little hair.
- Most epidermoid cysts arise in adult life.
- They are more than twice as common in men as in women.
- They present as one or more flesh–coloured to yellowish, adherent, firm, round nodules of variable size.
- A central pore or punctum may be present.
- Keratinous contents are soft, cheese-like and malodorous.
- Scrotal and labial cysts are frequently multiple and may calcify.
Epidermoid cyst is also called follicular infundibular cyst, epidermal cyst, keratin cyst.
- A cutaneous dermoid cyst may include skin, skin structures and sometimes teeth, cartilage and bone.
- Most dermoid cysts are found on face, neck, scalp; often around eyelid, forehead and brow.
- It is a thin-walled tumour that ranges from soft to hard in consistency.
- The cyst is formed at birth but the patient may not present until an adult.
- A ganglion cyst most often involves scapholunate joint of dorsal wrist.
- These arise in young to middle-aged adults.
- They are 3 times more common in women than in men.
- The cyst is a unilocular of multilocular firm swelling 2–4 cm in diameter that transilluminates.
- Cyst contents are mainly hyaluranic acid, a golden-coloured goo.
- Mucous/myxoid pseudocysts arise in older adults on distal phalanx
- They arise from distal interphalangeal joint, associated with osteoarthritis.
- They often present as a longitudinal depression in the nail due to compression on the proximal matrix.
Labial mucous/myxoid cyst
- A cyst in the lip may be due to occlusion of the salivary duct
- They are also called mucocoele.
- It is a soft to firm firm, 5–15 mm diameter, semi-translucent nodule.
- Hidrocystoma is a translucent jelly-like cyst arising on an eyelid.
- It is also known as cystadenoma, Moll gland cyst, and sudoriferous cyst.
- The common solitary translucent eyelid cyst is an apocrine hidrocystoma.
- Multiple cysts on the lower eyelid are eccrine hidrocystomas.
- Milia are 1–2 mm superficial white dome-shaped papules containing keratin
- Primary milia arise in neonates (50%), adolescents and adults; they are rarely familial and sometimes eruptive.
- Primary milia occur on eyelids, cheeks, nose, mucosa (Epstein pearls) and palate (Bohn nodules) in babies; and eyelids, cheeks and nose of older children and adults.
- Transverse primary milia are sometimes noted across nasal groove or around areola.
- In milia en plaque, multiple milia arise on an erythematous plaque on face, chin or ears.
- Secondary milia arise at the site of epidermal repair after blistering or injury, eg epidermolysis bullosa, bullous pemphigoid, porphyria cutanea tarda, thermal burn, dermabrasion.
- Secondary milia are reported as an adverse effect of topical steroids, 5-fluorouracil cream, vemurafenib and dovitinib.
- 90% of trichilemmal cysts occur on scalp; otherwise face, neck, trunk, and extremities.
- Most trichilemmal cysts arise in middle age.
- In 70% of cases, trichilemmal cysts are multiple.
- They presents as adherent, round or oval, firm nodules.
- There is no punctum.
- The keratinous content is firm, white and easily enucleated.
A trichilemmal cyst is also called pilar cyst.