Sunday, July 16, 2017

Sweet's Syndrome and Pathergy

These two lesions are different stages in the same condition. Sweet's syndrome is a curious hypersensitivity syndrome with a massive infiltrate of neutrophils into the dermis giving a pseudoblistering like lesion. The purple, exophytic lesion on the finger looks like Orf, a pox virus infection from sheep or a pyogenic granuloma or even a malignant tumour but it started as a pustule similar to that seen in image one. These pustules can arise at sites of injury such as needle stick injuries from taking blood where the phenomenon is known as pathergy. Patients showing Sweet's syndrome will have a significant leukocytosis in a blood count and sometimes fever and joint swelling. 20% of cases may be associated with a blood or solid organ tumour malignancy and also with inflammatory bowel diseases Crohns and Ulcerative colitis or even rheumatoid arthritis. In many recurrent cases though the cause is not known. Cases respond to oral steroids tapered over 3 weeks. Lesions will heal without scarring which is surprising looking at that finger!

Lichen Planus Purple Colour

Lichen planus is not a common skin disease but it does have a very characteristic purple colour which helps in making the diagnosis. The itchy purple polygonal papules can be seen individually on the volar wrist or joined up as plaques like this on the shins. Here chronic rubbing can make them thicken into purplish nodules which can be mistaken for squamous cell carcinomas both clinically and surprisingly histologically because of the pseudoepitheliomatous thickening of the epidermis. Usually small white lines called Wickham’s striae can be seen on the plaque surface in lichen planus and lesions may show some hyperpigmentation when partially healing but it is that purple colour which is so distinctive. Always check the buccal surface of the cheek for the typical white net like pattern of mucosal thickening seen in some cases particularly due to drugs such as thiazide diuretics. Many cases though are idiopathic possibly autoimmune but respond to strong topical steroids or intralesional steroids for nodules on the shins.

Perfume allergy

A rash behind the ear like this could easily have been diagnosed as seborrheic dermatitis. She had a similar rash behind her other ear. A bit of dandruff and some scale in the eyebrows would have confirmed your diagnosis. However this lady also had a rash on the volar aspect of both wrists and on the V of her neck. This distribution is typical of a perfume allergy. These were the areas where she applied perfume every morning before work. You can use a perfume for years before suddenly becoming allergic to one of the ingredients. Perfumes are a mixture of 20 plus different chemicals and these ingredients are not listed on the box. Hence other perfumes may cause the same reaction. Perfumes are found everywhere in our environment from toilets to lifts. Highly sensitive patients can react to these with asthma. If this patient wants to continue using perfume she should restrict it to putting it on her clothes not her skin!

Melanoma scalp

Hairy scalps are generally difficult areas to examine for skin cancers but you should at least examine the scalp margin, particularly over the forehead. As hair lines recede these areas are prone to solar keratoses, SCC in situ and basal cell carcinomas. Melanomas are less common and may be confused with pigmented seborrheic keratoses which are also commonly found at the scalp margin. With the fashion for close cropped hair in males it becomes easier to examine the hairy scalp but it also means these patients are not getting the solar protection from their hair that they once enjoyed! The patient above had just had a close side haircut which made this lesion more easily seen and diagnosed. It was still a thin, 0.3mm melanoma which was subsequently excised with 1 cm margins. The prognosis is excellent as is usually the case when melanomas are diagnosed early. However you will not find them if you don’t look!

Sunday, April 2, 2017

Rosacea steroid induced (Video)

We keep seeing this condition despite dermatologists repeatedly warning of the dangers of using a fluorinated steroid cream on the face for more than 7 days. This is steroid induced rosacea, in this case from mometasone but any fluorinated topical steroid can do it. There is overgrowth of a small mite called demodex in the skin which causes a generalised facial papular, sometimes pustular rash with curious sparing around the vermillion lip border. It really flares when the topical steroid is stopped but this has to be done to cure it. Also add in an oral tetracycline such as doxycycline 50 mgs bd and try some 2% sulfur in sorbolene cream bd topically. Within a week it will be improving but it often needs a month of therapy to see it settled completely without any scarring. The initial rash treated might have been seborrheic dermatitis but if it recurs then use any sulfur in sorbolene cream left! 1% hydrocortisone cream virtually never causes this condition.

Necrobiosis lipoidica (Video)

Rashes on the front of the shin are seen commonly with lichen simplex chronicus which is very itchy  and also with this condition, necrobiosis lipoidica diabeticorum (NLD). It is a condition you see in diabetics or pre diabetics. It is non scaling, not itchy and just slowly expands. The cause is not known but it is thought to be related to diabetes induced vascular damage. Although only about 22% of patients with NLD have diabetes those diabetics who also have NLD have an increased incidence of neuropathy, retinopathy and joint immobility. These lesions have recurred around a large plaque that had been treated with intralesional steroid injections into the inflamed edge. Most lesions have a raised edge and a central atrophic area where the underlying veins can be easily seen. Sometimes the underlying fat gives them a yellowish tinge. A punch biopsy of the edge should always be sutured as injuries here are very slow to heal. No other treatment has been shown to work in double blind trials.

Palmo plantar psoriasis (Video)

We are used to seeing patients with psoriasis present with large scaly plaques on the elbows, knees and lower legs but sometimes patients may only have psoriasis on the hands and feet and here the diagnosis is not quite so obvious. Overweight patients, who walk around barefoot or with open backed sandals, will often develop thick keratin build up on the heels where the keratin will dry and crack giving deep painful fissures. True psoriasis is usually more extensive as in this case with forefoot involvement and on the instep extending out on to the side of the foot. Fungal infection is always a differential diagnosis but in psoriasis the web spaces between the toes are spared. Patients should use closed in shoes and can try Daivobet ointment BD for a month but many patients require an oral retinoid such as Acitretin to peel away the scale first before using the calcipotriol steroid combination or narrow band UVB to prevent it recurring. 

Saturday, December 10, 2016

Lupus erythematosus Subacute

This looks a florid red non scaly rash. It could be many conditions including drug and viral exanthems. However the distribution of the rash helps narrow the diagnoses and suggest others. This rash was mainly on sun exposed areas, outer arms, V of the neck, lower legs below the dress line, sides of the face with sparing behind the ears. A photo distribution like this suggests a photo drug reaction particularly to thiazide diuretics or oral tetracyclines but also brings diseases such as lupus erythematosus into consideration. Discoid lupus is seen in sun exposed areas but is red and scaly. The red non scaly variants of lupus are either subacute or systemic. This patient had subacute lupus with positive ANAs and ENAs particularly the photo inducing Ro antibodies. A skin biopsy can help but the positive antibodies really make the diagnosis in the correct clinical setting. Treatment is sun protection with clothing and sunscreens, topical steroid creams and hydroxychloroquine until the rash settles. 

Male pattern alopecia

Early male pattern alopecia can be a major psychological problem to a young male. This 18 year old has early significant retraction of his anterior hair line and also had some occipital thinning. There was a family history of baldness but only in the grandparents. For this reason hormone studies were done including testosterone and dehydroepiandrosterone (DHEAS) in case of adrenal problems but these were all normal. He did not have hirsuitism elsewhere or bad acne and was not taking any gym steroid supplements.  Minoxidil topically or Finasteride orally will slow down the rate of hair loss in virtually all treated patients. However actual hair regrowth occurs in only 10% of  topical minoxidil and 20% of oral finasteride treated patients. The treatments are often combined. If hair regrowth occurs the treatments must be continued indefinitely or the regrown hair will fall out. Significant side effects are rare. Dutasteride is a new drug acting like finasteride but more effective and well tolerated.

Necrobiosis Lipoidica

Lesions on the anterior shin can be a skin cancer or psoriasis but if red non scaly with a raised edge then the likeliest diagnosis is necrobiosis lipoidica. This condition is most often seen in diabetics or pre diabetics where it starts as a small flat pink macule that gradually increases in size and develops a papular edge. The central epidermis may thin, allowing the underlying yellow of the fat to appear centrally with prominent veins. If this area is traumatised it ulcerates easily and is very slow to heal. For early lesions the best way to stop progression is to inject  Kenacort A10 diluted with 3 mls of local anaesthetic to 2.5 mgs per ml  into the lesion edge. This can be repeated after 4 weeks. Other measures are used to increase peripheral blood flow such as   Pentoxifylline or low dose aspirin and dipyridamole. Around 75% of patients who have necrobiosis lipoidica will ultimately develop diabetes mellitus.