Both Ends of the Spectrum in Dermatology

The BMJ this week includes two very different and contrasting dermatological conditions. In one hand there is the extremely common but relatively benign basal cell carcinoma, whilst at the other end is the rare but potentially fatal toxic-epidermolysis-necrosis occurring as a result of an adverse drug reaction.

Facial Basal Cell Carcinoma:

BCC is the most common human cancer. The incidence of BCC is increasing and the cost to the NHS of treating non-melanoma skin cancers is high. Timely recognition and treatment of BCCs usually results in excellent outcomes but specialist intervention is required for BCCs in difficult to treat areas. The definition of BCC is locally invasive cancer if the epidermal basaloid cells. Up to 85% of BCCs are found on the head and neck. Early recognition can limit the extent of facial tissue involvement. The main risk factor for development of BCC is exposure to UV light, explaining why there are such geographical variations in the incidence of the cancer with sun exposure in childhood being of particular importance. BCCs are more common and more aggressive in men compared to women. BCCs are less likely to occur in pigmented skin due to the protection provided by melanin. Immunosuppression and radiotherapy are other risk factors.  Most patients describe a non-healing 'lump' or 'sore spot' which grows slowly but is otherwise asymptomatic. 

Different subtypes of BCC are: nodular, nodulo-ulcerative, superficial, morphoeic, or infiltrated and pigmented. Nodular BCC is the most common type found in the UK. Classic features include: overlying telangectasia, central crusting, raised rolled edge and ulceration. Following diagnosis, the risk of a further BCC is 10x greater than the general population. The differential diagnosis includes: solar keratosis, SCC, seborrhoeic keratosis, intradermal naevus, psoriasis and eczema. High risk BCCs are those >2cm in diameter, located in high risk anatomical areas, poorly defined edges and recurrent or poorly defined BCCs. Treatment options include wide local excision, MOHS microgaphic surgery, radiotherapy, photodynamic therapy, imiquimod, curettage and cautery, cryotherapy and lasers. Wide local excision can be used to treat most facial BCCs as long as there is a successful clearance margin. Most BCCs grow slowly and follow a non-aggressive course but if neglected for a long time they can offer a therapeutic challenge. 

Toxic Epidermolysis Necrosis:

A patient is prescribed amoxicillin for a sore throat and mouth. Five days later he is admitted to the general medical ward with a fever and rapidly spreading burning rash on his trunk, palms and soles. He also has painful red eyes and inflamed ulcers in his mouth. The next day he develops blisters and loss of the top layer of his skin on gentle touch. He then developed respiratory failure, requiring intubation and transfer to the Intensive Care Unit. 

The diagnosis is a severe adverse cutaneous drug reaction with epidermal detachment, classified as Stevens-Johnson syndrome - toxic epidermal necrolysis overlap. The diagnosis is confirmed by taking two skin biopsies - one for immediate cryosection and one for confventional formalin fixed analysis. Skin biopsy shows detatchment of the epidermis from the dermis and apoptosis of keratinocytes. The main causes of this syndrome are drug hypersensitivities but others include infections eg. Herpes Simplex Virus. Management is to withdraw the offending drug and provide supportive care in an intensive care environment with special attention to fluid resuscitation, skin care and eye care.