A series of 782 patients with a clinical diagnosis of oral or lip leukoplakia was followed with regular checks for 1 to 44 years (mean 12 years). Oral carcinoma developed in 2.4% of the patients in 10 years and in 4% in 20 years. The prevalence in the various age groups was about 50 to 100 times greater than for the Swedish population according to the 1959 Cancer Registry. It was primarily the small group of cases of leukoplakia in persons not using tobacco that were responsible for the excess morbidity from oral carcinoma; among tobacco users with leukoplakia the figure was considerably lower. There is no evidence the the incidence of oral carcinoma can be diminished by surgical removal of the leukoplakia but this does not mean that the operation should be abandoned, mainly for histologic diagnosis. The prevalence of other malignant tumors than oral and lip carcinoma in cases of oral leukoplakia did not differ from that of malignant tumors in the Swedish population as a whole.

The morphology of the hair bundles on top of the receptor cells in the lateral line organ of the teleost fish Lota vulgaris is described. Each receptor cell shows a distinct morphological polarization. Two groups of receptor cells can be distingiushcd, one consisting of cells polarized towards the head, the other consisting of cells polarized towards the tail. In the crista ampullaris all cells are polarized in the same direction. An hypothesis is proposed for the function of the receptor cells in the lateral line organ and the labyrinth based on a correlation of morphological and functional polarization.

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Background. Results of surgical treatment of cutaneous malignant melanoma (CMM) have been highly variable, probably because of patient selection. Therefore, a study of representative patients with this disease was performed. Methods. In a defined area of Sweden, 581 patients were analyzed. Clinical records and histopathologic findings were reviewed. The minimum follow‐up time was 7 years. Prognostic factors were evaluated by the Cox proportional hazards model. Results. Evaluation of sex distribution, age, and anatomic site of the primary tumor showed that the patients were representative of all Swedish patients with CMM of the head and neck. The mean patient age at diagnosis was 64 years for both sexes. Fifty‐three percent of the patients were women. Female patients had more tumors of the face than did male patients, whereas male patients were overrepresented among patients with tumors of the auricle‐external ear canal and scalp‐neck area. Localization to the face was observed in 68%, which is an overrepresentation of three to four times when skin surface is taken into consideration. Twenty‐four percent of the patients had lentigo maligna melanoma. Only 33% of the patients had superficial spreading melanoma. In univariate analyses, sex, anatomic site of the primary tumor, histogenetic type, Clark level of invasion, and tumor thickness had prognostic power. In a multivariate analysis, tumor thickness, anatomic site of the primary tumor, and sex of the patient were independent prognostic factors. Conclusions. In representative patients with CMM of the head and neck, tumor thickness, anatomic site of the primary tumor, and sex of the patients were independent prognostic factors.