Temporal change in diagnostic criteria as a cause of the increase of malignant melanoma over time is unlikely.

To assess whether the increase in malignant melanoma incidence could be due, at least in part, to changes in histological criteria of malignancy, pathologists in Australia, France, Italy, New Zealand, Norway, Sweden, the United Kingdom, the United States and the USSR reviewed diagnoses of 50 consecutive pigmented naevi (40 junctional and compound; 10 intradermal) and 20 consecutive malignant melanomas made in each participating centre around 1930, around 1955 and around 1980. Collaborating pathologists re-read the material, 2,665 cases in all, either from the original slide (82%) or from a recut block (17%), gave their diagnosis and indicated whether the lesion was benign (B), dubious benign (DB), dubious malignant (DM) or malignant (M). As the distribution of review diagnoses was much the same whether the original slide or one made from a recut block was read, the material was pooled. Overall, 2.8% of cases originally reported as B/DB were reviewed as DM/M, while 4.4% of the DM/M diagnoses were held to be B/DB. The shifts between categories were greatest around 1955 and least around 1980, suggesting increasing uniformity of interpretation. All available blocks were recut and sections sent to IARC for review: 1.7% (22) of 1293 B/DB diagnoses were considered to be DM/M and 3.3% (18) of 551 DM/M diagnoses were considered to have been B/DB. The consistently low frequency of shift in diagnostic category, whether the material was reviewed in the collaborating laboratories or by one pathologist at IARC, in a study designed to give maximum attention to those lesions--the junctional and compound naevi--in which a change in opinion as to malignancy would be most likely to arise, suggests that pathologists, irrespective of geographical location, are using common criteria. These findings argue against changes in histological interpretation as being responsible for more than a small portion of the continuous increase of some 3% to 8% per annum observed in malignant melanoma incidence. Other explanations, such as an increase in the frequency or potential for malignant transformation of precursor lesions, must be sought. The anatomical distribution of the malignant melanomas examined followed the usual site pattern by sex, and their thickness was observed to decrease over the period of the study in most centres.

Aggressive angiomyxoma of the female pelvis.

A 42 year old female presented with a 6 year history of a perineal mass. Clinically it had all the features of a perineal hernia. Two previous attempts to repair the 'hernia' had been performed. At operation an aggressive angiomyxoma of the female pelvis was identified and resected via an abdomino-perineal combined approach. The case is discussed with reference to the literature.

Granulomatous angiitis of the central nervous system.

Granulomatous angiitis of the nervous system is a rare necrotizing vasculitis that is largely confined to the central nervous system. The case of a 43-year-old patient is presented and the clinical presentation, diagnostic difficulties and treatment are discussed. Patients present in their fourth decade with diffuse and focal neurological symptoms and signs. No single test is diagnostic; however, cerebrospinal fluid lymphocytosis and raised protein levels, changes on cerebral angiography, and leptomeningeal biopsy may confirm the diagnosis. Although the administration of corticosteroid agents has prolonged the survival of the patient, a progression of the disease has been the rule. The administration of corticosteroid and cyclophosphamide agents on alternate days may lead to clinical remission of the disease.

Cysticercosis of the superior oblique muscle.

A 39-year-old Vietnamese refugee with upper eyelid swelling followed by vertical diplopia and mild proptosis was shown by computerised tomography to have a localised lesion in the region of the right superior oblique muscle. At operation, this was a cyst and histology confirmed the larval form of Taenia solium (cysticercosis).

Double pylorus: a complication of chronic gastric ulcer?

A case of double pylorus with a chronic ulcer in one of the two channels is described. The patient, a middle-aged man with active rheumatoid arthritis, required partial gastrectomy to allow continued treatment of the arthritis with anti-inflammatory drugs. Detailed histological examination of the surgical specimen revealed features consistent with intramural penetration of an ulcer across the pyloric ring, resulting in a gastro-duodenal fistula. The findings provide further support for the hypothesis that the double pylorus is an acquired lesion, which occurs as an uncommon complication of chronic peptic ulcer.

Visual failure during replacement therapy in primary hypothyroidism with pituitary enlargement.

A 34-year-old woman with longstanding untreated thyroprivic hypothyroidism and pituitary enlargement is reported here in whom visual failure coincided with thyroid hormone replacement. Visual fields were normal after 30 years untreated hypothyroidism, but severe concentric field constriction developed during the first 6 months of therapy and was relieved by hypophysectomy. Plasma TSH and prolactin remained elevated during 10 months replacement therapy, but both were suppressed by preoperative hyperreplacement with T3 and T4. The paradoxical pressure symptoms suggest imbalance between pituitary TSH content and TSH release during treatment with thyroid hormone; a finding previously reported in animal studies. This sequence suggests that patients with known pituitary enlargement secondary to thyroid hypofunction should be observed for pressure symptoms during thyroid hormone treatment.

Use of tissues embedded in epoxy resin for routine histological examination of renal biopsies.

The production of 0.4mu thick, full-length sections from renal tissue taken by needle biopsy is achieved by formalin and osmic acid fixation and embedding in epoxy resin as for ultramicrotomy. The marked improvement in histological clarity by using this technique is illustrated by comparison with material embedded in paraffin.