The ultrastructural characteristics of mucin production in mammary mucoid carcinoma, signet ring cell carcinoma (Harris, Wells & Vasudev 1978), papillary carcinoma and lobular carcinoma are compared. The mucin in lobular carcinoma is confined to intracytoplasmic lumina whereas it is present as membrane bound granules in the other three types, although intracytoplasmic lumina also occur in the latter. A possible origin of intracytoplasmic lumina from distended Golgi cisternae is proposed. Possibly, extracellular mucin acts as a mechanical barrier between tumour cells and lymphatics, thus explaining the good prognosis of typical mucoid carcinomas.

A case of pneumatosis intestinalis studied by light and electron microscopy is presented. The cysts are dilated lymphatic vessels. Abundant fine fatty globules are found in the cysts and in the histiocytes and multinucleated giant cells which line the lymphatics and which are present in the interstitium. The giant cell formation and florid histiocytic reaction are most probably due to leakage of fatty material from the dilated lymphatics.

CT scan showed that the right adrenal gland appeared larger than the left adrenal gland. Scintigraphy with radioisotope-labelled cholesterol showed uptake only in the region of the right adrenal. In view of the radiological and biochemical findings it was thought that she had a right-sided adrenal tumour. A right adrenalectomy was performed. The gland appeared normal in size and showed many micronodules but no adenoma. The provisional diagnosis was revised to that of micronodular adrenal disease and since this is usually bilateral, it was thought advisable to remove the remaining adrenal. After the second operation the clinical features of Cushing's syndrome resolved and regular menses returned. PATHOLOGYThe right adrenal weighed 8-2 g, the left 5.3 g. The appearance of both glands was similar. There were numerous nodules, some black and others yellow set in a yellow cortex. The largest nodule measured 1 x 0-5 cm. The right adrenal was fixed in Carson's fluid. Small blocks (1 mm3) were taken from the left adrenal and fixed in 4% glutaraldehyde in Sorenson's phosphate buffer at 4°C. The blocks were post-fixed in 1% phosphate-buffered osmium tetroxide. The material was embedded in Epon resin. Sections (1 gm) were cut and stained with toluidine blue. Thin sections were cut on an LKB IV ultramicrotome, stained with uranyl acetate and lead citrate and examined on an AEI EM810 electron microscope.Blocks from the right adrenal were first washed in cacodylate buffer, post-fixed in osmium tetroxide and embedded in Epon resin as above. Blocks were taken from both the yellow and black areas.On light microscopy the presence of nodularity 1078 on 11 May 2018 by guest. Protected by copyright.

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