Desmoplastic trichepithelioma is a benign skin adnexal tumour and is a type of trichoepithelioma that tends to occur in childhood, arising on the face of children or young adults.

Trichoblastic fibromas are benign skin adnexal tumours, occur between the 5th and 7th decades on the head and neck.

Trichoadenomas are benign and a type of trichoepithelioma. They are solitary lesions arising on the faces of adults.

This video is about the classical trichoepithelioma. These are benign skin adnexal tumours that show hair follicle differentiation. They are composed of basaloid cells, horn cysts may be present and foreign body giant cells and granulomas may be seen as a reaction to liberated keratin from ruptured horn cysts. Trichoepitheliomas may be solitary or less frequently multiple with an autosomal dominant inheritance. The main differential diagnosis is basal cell carcinoma.

Localised tenosynovial giant cell tumours are benign and also known as giant cell tumour of tendon sheath, benign synovioma and localised pigmented villonodular synovitis. They are twice as common in females than males, tend to occur in the 20s to 40s particularly on tendons in the fingers.

Chondroid syringomas are benign adnexal tumours that arise on the skin of the head and neck of adults slightly more frequently in females.

Synovial chondromatosis is also known as synovial osteochondromatosis. It tends to affect young men with the knee being the most frequently affected joint.

Onchocerciasis is also known as river blindness. It is caused by infection with Onchocerca Volvulus. This is a microfilarial nematode (worm). Black flies that breed along streams and rivers transmit the parasite from ingested blood from people already infected with the disease. Onchocerciasis is the commonest cause of preventable blindness in Sub-Saharan Africa.

Diffuse Tenosynovial Giant Cell Tumour is also known as pigmented villonodular synovitis

Plexiform schwannomas are also known as plexiform neurilemmomas. They are benign tumours derived from the nerve sheath.

Solitary fibrous tumours were previously known as haemangiopericytomas. Most of them have benign behaviour.

Fibroma of tendon sheath is an uncommon lesion occurring more frequently in young or middle aged males than females, usually on the fingers. They are benign. Treatment is by excision but they may recur in around 10% of cases.

Spindle cell lipomas occur most frequently in elderly men arising on the back, back of neck and shoulders.

Pseudoepitheliomatous hyperplasia is also known as pseudocarcinomatous hyperplasia because of its resemblance to squamous cell carcinoma. This is a short video about the causes and histological features of pseudoepitheliomatous hyperplasia

What are polyps? They are excrescences that protrude. They often arise from the mucous membranes for example adenomatous polyps of the colon.

Erythema nodosum is a type of panniculitis that occurs most frequently in females 25 - 40 years old. The usual site is the anterior aspect of the lower legs. It is associated with many conditions including beta haemolytic streptococcal throat infections, ascoid, TB, leprosy, inflammatory bowel disease, sulfonamides, oral contraceptive pill, pregaancy, amoebiasis, histoplasmosis etc. The lesions are red, nodular, painful and there may be feever, muscle and joint pains.

Papillomas are very common benign lesions that arise from epithelial surfaces.

Eccrine poromas are benign adnexal skin tumours that arise most frequently on the soles and sides of the feet

This useful video explains how to grade breast cancer and is presented by Professor Ian Ellis, University of Nottingham. Examples of different grades are included.

Eccrine porocarcinomas are also known as malignant eccrine poromas. They are rare, affecting males and females equally and the age tends to be in the 60s. Eccrine porocarcinomas have a tendency to spread through the skin and may also cause visceral metastases.