Saturday, May 18, 2019

Melanoma




It is always important to examine the ears carefully when carrying out a skin check.  This small pigmented lesion was a regressed invasive melanoma 0.2 mm thick. The patient was entirely unaware of it’s existence. Men are particularly susceptible to solar damage on the ear because of their short hair. It is exacerbated by only wearing a baseball cap rather than a brimmed hat. It is a good idea to run your finger over the surface of the pinna. This will pick up small solar keratoses better than just visually examining the ear.  Always examine the junction of the ear with the skull posteriorly. Basal cell carcinoma can arise here and go deep into this embryonic fusion area. Another area to look at carefully is in the conchae around the external auditory meatus. Again men are more likely than women to develop BCCs in this area and if it is an infiltrating BCC and it starts to grow into the external meatus and down the auditory canal, then the patient is in real trouble.  Note also that squamous cell carcinomas of the ear are more likely to metastasise than many other areas of the body and so should be excised widely and early.

Tinea corporis


Extensive red scaly rashes like this are often misdiagnosed as a form of dermatitis and treated with a strong topical steroid cream. Initially this seems to work. The redness goes and the scale is less prominent but as soon as the cream is ceased the rash returns, more irritable than ever. The scale takes longer to reform and the rash covers a bigger area than before! This sequence of events should make you think you are dealing with a tinea corporis infection. If the old adage of always taking a skin scraping for microscopy and culture of all red scaly rashes had been followed at the outset, before prescribing the topical steroid, then the diagnosis would have been made much earlier. This patient was predisposed to a tinea infection by being on Methotrexate for rheumatoid arthritis but the situation is also seen in diabetics or patients on oral steroids or other immunosuppressing drugs or conditions. Patients usually start with fungus in the groin or between the toes and by scratching these areas transfer fungus to other areas of the body. He grew Trichophyton rubrum, a very common anthropophilic fungus which often presents just with scale and redness and very little inflammation. It is usually picked up from another human being . Fungi acquired from animals elicit a more marked inflammatory reaction. He was treated with oral terbinafine 250 mgs daily for 6 weeks.

Darier's disease


The hot, humid days of summer can exacerbate many skin diseases but probably none so much as Darier’s disease. Friction increases in flexural areas with excess sweating leading to epidermal thickening and skin splitting with superimposed candida and often staph infection. You can see this under the breasts in this case with the surrounding satellitosis of candida superinfection. Dariers is also prominent in other mainly sebaceous areas such as behind the ears and on the anterior chest presenting as greasy brown scaly papules. The condition is inherited as an autosomal dominant so it is seen equally in males and females. The most effective therapy we have is acitretin, an oral  retinoid which reduces the excessive skin thickening but you still need topical steroids, topical antibiotics and anti yeast creams to suppress the inflammation and infection. Acitretin cannot be used in menstruating females who may fall pregnant as the drug is teratogenic and can remain in the system for 18 months after being stopped. Always check the nails of someone suspected of having Dariers as they often show longitudinal red streaks with a notch at the nail edge. This condition can clear remarkably in the winter months and patients are always better in cooler climates. 

Varicella


Sometimes common conditions are difficult to diagnose when we see them out of context. Varicella is rare in immunized children but we sometimes see it in a modified form in children previously vaccinated or in young adults. This man was in his 70s , immunocompetent and had never had varicella as a child or been vaccinated. He presented with a fever and malaise and a series of vesicles on a red base at different stages of development. In a dermatomal distribution this rash would have been diagnosed as herpes zoster but generalized here it was late onset varicella. His aged mother in law had recently had herpes zoster and he had been in contact with her. He was admitted to hospital and treated with IV acyclovir for a few days and then oral valacyclovir. If the patient had mentioned he had never had chickenpox he could have been vaccinated after his contact with zoster in his mother in law and this would have prevented him developing varicella. Varicella is often more severe in adults with pneumonia and encephalitis being feared complications. An injection of zoster immune globulin within 96 hours of exposure to the virus can prevent the disease developing but is usually only given to immunosuppressed patients.

Lymphoedema


Lymphoedema is becoming a common problem in elderly patients who develop cancer in the groin or axillary nodes and have a node clearance. This is likely to follow breast or melanoma surgery but also can occur after sentinel lymph node examination. The lymphedema gives a heavy swollen limb that interferes with walking or sport but also predisposes to infection such as cellulitis and makes any subsequent skin cancer excisions on the limb very difficult. However it is the chronic skin changes that are particularly troublesome. The epidermis thickens and thick crusts of keratin and serum build up on the surface. These can be removed with 4% Salicylic acid in sorbolene cream applied nocte. The skin surface becomes hard and may crack, oozing lymph fluid. Sometimes the fluid pressure raises pseudo blisters in the skin. If the skin is oozing with a secondary stasis dermatitis then a topical steroid cream such as 0.02% betamethasone with some mupirocin cream should be used twice daily. Once the eczema is controlled efforts should be made to try to reduce the lymphedema by compression bandaging or the process will just relentlessly progress. The immobility caused by the lymphedema leads to obesity which just compounds the problem. The best approach is to treat the condition early with massage and compression bandaging to prevent these later changes occuring . The mossy leg syndrome is an extreme example of the skin changes of chronic lymphedema where the name accurately describes the surface appearance of the skin!

Sunday, September 23, 2018

Atrophie blanche




A white area like this on the lower leg surrounded by light brown pigmentation and dot petechiae is called atrophie blanche. It is seen particularly in overweight diabetic patients with stasis dermatitis. The white area of skin is often firm due to underlying scarring and fat damage or panniculitis. Biopsies here are slow to heal but may show a segmental vasculitis. Treatment is difficult. The skin is already scarred and this will not change. However further damage can be reduced by dealing with the stasis through weight loss and support stockings and treatment of underlying varicose veins. Various vasodilator drugs have also been tried but the basic issues have to be remedied first to have any chance of success. Some cases of this condition occur after a definite vasculopathy with focal thrombosis in dermal vessels presenting with leg ulcers. This variant can be treated with aspirin, warfarin or low dose heparin.

Toxic epidermal becrolysis




This looks like a really bad burn but it is due to a drug! The condition is known as toxic epidermal necrolysis where a drug binds to the skin setting up a type 2 immune reaction where  the immune system attacks both the drug and the epidermal cell it is attached to. The result is full thickness epidermal necrosis where the epidermis just sloughs off from the underlying dermis. However equally severe reactions occur on mucosal surfaces with the lips, eyes, genital and perianal surfaces all eroding and crusting. The skin is very painful to touch and must be gently handled to prevent further skin sloughing. Patients are usually managed in a Burns unit where expert care can be given. Intravenous immunoglobulin and a drug called Rituximab which reduces antibody production give the best results but death can occur in around 30% of severe cases. This case was caused by 2 weeks of Sulfonamide for a bladder infection.

Shitake flagellate dermatitis




This is an unusual streaky rash seen on the back and abdomen. It arose following a meal of Shitake mushrooms. This is a distinctive rash described as a flagellate dermatitis. It follows the ingestion of raw or undercooked shitake mushrooms. These are popular mushrooms in Asian cooking but a rash may only occur in around 2% of people consuming them raw or undercooked. Sometimes the lesions do not blanch because lentinan, a thermolabile polysaccharide releases interleukin 1 which causes vasodilatation and haemorrhage. Linear petechiae can be seen elsewhere on the hands and feet. Localised swelling and fever can also occur. The rash will resolve spontaneously over a couple of weeks but some oral steroids early in the rash will help it resolve more quickly. It is the distinctive streaky nature of the rash that suggests the diagnosis. Bleomycin may cause a similar flagellate eruption but it resolves with hyperpigmentation.

Lichen simplex chronicus neck




This is the base of the neck posteriorly. It is a common site for stress induced scratching. When skin is rubbed or scratched repeatedly it thickens or lichenifies. Sometimes the skin markings just become more prominent but in other cases grouped papules and nodules are formed. This is more common in people of an Asian background with a history of atopic eczema. Unless the itch scratch cycle is broken this rash will persist indefinitely. You need to use a very strong topical steroid such as Diprosone OV cream or ointment to break that cycle by reducing the itch. Another option is to use diluted intra lesional Kenacort A10 with 1ml of solution to 3 mls of local anaesthetic. A small amount is injected intradermally at 1 cm intervals covering the area. This slowly diffuses over a 4 week period reducing the itch and the skin thickening. It helps to point out the cause and to instigate measures to help with the underlying stress.

Psoriasis flexural




We are used to psoriasis being a red scaly disease but when it involves the flexures the scale is much less apparent. The moist occluded surfaces mitigate against any scale formation but tend to encourage some secondary candida on the damaged moist surfaces. Sometimes these candida lesions present as satellite pustules with isolated pustules seen a few centimeters away from the main rash on a background of normal skin. Combination creams with 1% hydrocortisone and an antifungal preparation such as clotrimazole are ideal for treating both the psoriasis and the secondary candida. Stronger fluorinated topical steroid creams should not be used in these flexural occluded areas as absorption is enhanced and skin atrophy with striae formation can occur surprisingly quickly within weeks. Weight loss and having cotton between the breast surfaces to absorb sweat can help the condition resolve more quickly. Sometimes a tinea fungal infection can mimic this rash so taking skin scrapings of the edge for microscopy and fungal culture is always a good idea.