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Monilethrix is characterized by beaded or moniliform hair, which results from the periodic thinning of the hair shaft. The beaded hair thus produced is subject to excess weathering and premature fracturing at the internodes. Clinically, monilethrix presents with short, fragile, broken hair. The follicular abnormalities range from subtle perifollicular abnormalities range from subtle perifollicular erythema and hyperkeratosis to horny follicular papule formation. At the ultrastructural level, cytolysis and keratin tonofilament clumping (epidermolysis) are seen in the cortical cells of the bulb of the hair follicle. Microsatellite markers flanking the keratin gene clusters at 17q12-q21 and 12q11-q13 were used to perform linkage analysis in a monilethrix pedigree. This study demonstrates linkage of monilethrix in a pedigree to microsatellite DNA loci mapping to the region on chromosome 12 containing the type II keratin cluster. A major group of structural hair proteins, the basic type II trichocyte keratins, map within this epithelial cytokeratin gene cluster. This study implicates a mutation in a trichocyte keratin gene in the pathogenesis of a structural hair disorder.

Forty two women with hidradenitis suppurativa were assessed clinically and biochemically for evidence of androgen excess. Thirteen had irregular menses; 22 of 36 experienced exacerbation of hidradenitis suppurativa premenstrually; 19 had or had had acne vulgaris; and seven were hirsute. Comedones (blackheads) were found in apocrine sites in 37, but also in retroauricular sites in 18 and were considered to be an important physical sign for early diagnosis. Eight had evidence of pilonidal (postanal) sinus. The patients had a higher concentration of total testosterone (p less than 0.01) and free androgen index (testosterone to sex hormone binding globulin concentrations) (p less than 0.01) than normal controls. Patients with hidradenitis suppurativa appear to have endocrine abnormalities sufficient to suggest an androgenic basis for the disease.

A case of naevoid hypotrichosis affecting two symmetrical areas in the parietal regions is described.

In a study of the time course and nature of the sensory loss after cryosurgery the forearms of nine normal subjects were treated with liquid nitrogen using freeze times currently employed in clinical practice in Britain. Ability to appreciate touch, pinprick, and cold in the treated areas was tested at regular intervals and biopsy samples taken to investigate the pathogenesis. Appreciation of all three modalities of sensation was initially reduced in all nine subjects for all freeze times, yet complete recovery occurred in the seven patients completing follow up. This recovery, however, took up to one and a half years for the longest freeze, with even a 10 second freeze taking up to 10 months. Patients may be reassured that sensory loss after cryosurgery for up to two periods of 30 seconds will almost certainly recover, though it may take up to 18 months to do so.

Cryosurgery has been recommended for the treatment of cutaneous neoplasms, including benign and malignant melanocytic tumors. The main side effect of this treatment is pigment disruption which may be prolonged. There are no quantitative studies on melanocyte distribution after freeze injury. In this study the effect of standardized freeze times on melanocytes in guinea pig skin (tricolored) is described at the anatomic level and at the light and electron microscopic level. Melanocytes are quantified in epidermal sheets following dopa staining at 1-, 2-, and 3-month intervals after freezing. All the lesions were initially hypopigmented with a peripheral rim of hyperpigmentation. This was a transient phenomenon associated with an absence of melanocytes. Pigment migrated into the lesions so that after 3 months all the lesions on black skin were diffusely hyperpigmented. Pigment was slower to return to the red skin. Hair follicles were destroyed in the center of the lesion. The epidermal sheets demonstrated that the hyperpigmentation was an epidermal phenomenon and was associated with increased numbers of melanocytes (p less than 0.001). These melanocytes were distributed evenly throughout the lesion in contrast to the irregular distribution in normal skin.

Two cases of the basal cell naevus syndrome in association with an intracranial meningioma are described and the relationship discussed.

The pattern of hair growth, morphology of the hair shafts, and the hair root state are described in four girls and two boys with prepubertal hypertrichosis. The exact nosology of this form of excessive hair growth is discussed in relation to hirsuties and the possibility of it representing an 'atavistic' trait.

Ingrowing toenails are a common debilitating condition and often require surgical intervention. In 44 patients liquid nitrogen spray cryotherapy produced a rate of success comparable with that of other nail sparing techniques but had the advantage of being a quick, simple, and cheap outpatient procedure that could be carried out with limited facilities and without anaesthesia.

Twisted hairs as seen in pili torti have been observed on the abdomen and thighs of hirsute men and women. The occurrence of twisted hairs in persons without the syndrome of pili torti is discussed.

A case of porphyria cutanea tarda induced by oral contraceptive pill therapy is reported, and its unusual presenting sign of onycholysis of the finger nails is noted. Reference is made to the rarity of nail changes in porphyria and the regression of the onycholysis in the patient following therapy is outlined.

The treatment of vascular naevi with lasers is widely practised. The concept of specific vascular damage was an early ideal but it is much harder to attain than had been anticipated. The favourable results achieved by coagulation necrosis of the epidermis and upper dermis with the argon and CO2 lasers prompted us to try to produce the same changes with non-laser radiation. We have used an infra-red coagulator to treat flat vascular naevi and ectatic blood vessels. The handpiece which looks like a gun has a light guide capped by a 6 mm diameter sapphire. This size combined with a pulse duration of less than 1.0 second enables large areas of skin to be treated quickly. Preliminary results are presented.

Azathioprine was given to 11 patients with pemphigoid who had been on long-term maintenance therapy with prednisone or prednisolone. In nine of these prednisone therapy was withdrawn and all were maintained symptom-free on azathioprine alone, while in two the dose of prednisone was considerably reduced. One patient who had never received corticosteroids was controlled by azathioprine alone during the initial acute phase of the illness. Since azathioprine acts slowly, it is recommended that corticosteroids should be used together with azathioprine during the acute stage. Thus azathioprine is valuable in long-term management of pemphigoid, particularly in patients showing corticosteroid toxicity or in whom the minimum maintenance dose is dangerously high.