Summaries of papers 13

The SER was measured using the gravimetric method of Strauss & Pochi (1961) in 15 female and29 male patients, aged 18-81, and 200 control patients with warts or other localized dermatoses. TheSER was expressed as a percentage of the control values matched for age and sex. The mean SER ofthe male patients was normal (94%±s.d.4o), but that ofthe female patients was reduced to 51%its.d.30 and this decrease was highly significant (P<o-ooi).

SSL was obtained from the uninvolved forehead skin of 19 female and 32 male patients by thecup method using ether as a solvent, and was analysed by quantitative thin layer chromatography,using the method of Pye et al. (1976). The results obtained were compared with normal age matchedcontrols but no major abnormalities in sebum composition were detected. Minor changes were foundif the samples were taken from scaly red skin of the scalp, but these were not specific for seborrhoeicdermatitis, being found in other scaling scalp dermatoses such as psoriasis.

These results do not support the idea that seborrhoeic dermatitis is associated with seborrhoea or achange in SSL composition.

REFERENCES

Pyn, R.J., MEYRICK, GAY & BURTON, J.L. (1976) Skin surface lipid composition in rosacea. British Journal ofDermatology, 94, 161.

STRAUSS, J.S. & POCHI, P .E . (1961) The quantitative gravimetric determination of sebum production. Journalof Investigative Dermatology, 36, 293.

Arsenic and cancer

SUSAN EVANS

Department of Dermatology, University of Liverpool

Environmental, medicinal and occupational exposure to arsenic suggests that it is carcinogenic to manalthough animal experiments lend little support (Geyer, 1898; Hutchinson, 1S88; Roth, 1957;Sanderson, 1963).

One hundred and forty-four subjects who had received medicinal arsenic have been investigated.They were examined clinically for evidence of malignant and pre-malignant arsenical lesions andarsenic levels were measured by neutron activation analysis on samples of unaffected skin. Thesewere also subjected to tissue culture to observe cytogenetic effects. These results have been correlatedwith the age of the subjects, the length of exposure to and dosage of arsenic and the length of timesince therapy started.

Premalignant keratoses occurred in 64 subjects (44%) and malignant tumours were found in 17(12%), 6 of whom had multiple cancers.

The mean skin arsenic level was elevated but in those who had developed a carcinoma and wereolder it was reduced, despite the fact that they had ingested more arsenic. Chemically induced tumourshave a long latent interval and in this study it was 21-47 years. Various chromosomal abnormahtieswere found and the mean percentage total chromosomal damage was significantly greater than in thecontrols.

Thus arsenic in man is both mutagenic and carcinogenic and its use as a medicine, except in theelderly, is to be condemned.

14 Summaries of papers

REFERENCES

GEYER, L . (1898) Uber die chromischen Hautveranderungen beim Arsenicismus und Betrachtungen uber dieMassenerkrankungen in Reichenstein in Schlesien. Archiv fiir Dermatologie und Syphilis, 43, 221.

HuTCHiNSON, J. (1888) On some examples of arsenic keratosis of the skin and of arsenic cancer. J. Trans, path.Soc. hand., 39, 352.

ROTH, F . (1957) The sequelae of chronic arsenic poisoning in Moselle vintners. German Medical Monthly, 2Qirne), 172.

SANDERSON, K.V. (1963) Arsenic and skin cancer. Transactions of the St John's Hospital Dermatological Society,49) 115-•

Variations in ultrastructural appearance of Langerhans cells of normal human epidermis

A.S.BREATHNACH

St Mary's Hospital Medical School, London

The strong possibility that Langerhans cells are involved in immunological reactions of the skinredirects one's attention towards their appearance in normal epidermis, and to dimly recollected butpreviously inadequately considered features which now appear in a different light, and may haveconsiderable significance.

^Observations were carried out on clinically normal skin of subjects in good general health, and twotypes of cell with Langerhans granules were distinguished. The one can be described as classicallydendritic in shape with moderately electron-lucent cytoplasm, numerous Langerhans granules, andmoderate numbers of lysosomes and mitochondria, both of which tend to be concentrated locally.Such cells are present at all levels below the granular layer, and occasionally are seen to be directlyapposed to small mononuclear cells. The second type is less dendritic, occurs more frequently in thebasal layer, though also present suprabasally, has a much more electron-dense cytoplasm, much fewerLangerhans granules, but more numerous mitochondria, many of which may be swollen with loss ofcristae and vacuolation. Cells of both type may be seen in the same area of a section of well-fixedmaterial and cells with features intermediate between the two may be seen. The second type bears astriking resemblance to cells with Langerhans granules observed within the general dermis andlymphatics of actively and passively sensitized guinea-pigs, and of patients with striae distensae, andpityriasis versicolor. Lymphocytes, and cells which one would class as 'histiocytes', or cells of meso-dermal type, can be observed traversing the epidermal-dermal junction of clinically normal humanskin.

These observations can be given a variety of explanations. They could suggest a turnover of epi-dermal Langerhans cells with elimination of worn-out elements via the dermis; that these cellsnormally subserve a continuous monitoring role with respect to external antigen, or, that the popula-tion of epidermal Langerhans cells is not fully reproductively self-maintaining, but may occasionallybe augmented by recruitment from the dermis of cells of mesodermal type, which undergo fulldifferentiation (i.e. develop the characteristic granules) after they have entered the epidermis.