The present study, based upon the retrospective evaluation of 352 patients with primary myelodysplastic syndrome (pMDS), revealed hypoplastic MDS in 42 patients (11.9%). Median age is similar in hypo- and normo-/hypercellular MDS (72.6 versus 70.7 versus 72.4 years). Hypoplastic MDS occurred significantly more often in women compared with normo- and hypercellular MDS. Sequential biopsies were performed in 14 patients, showing a persistence of hypoplasia over a period of up to 43 months. The proportion of patients showing mesenchymal reaction, especially an increase of mast cells, was significantly higher in hypoplastic MDS, whereas dysplastic features of hematopoiesis occurred less frequently and were of lower grade in comparison to normo-/hyperplastic MDS. Among the subgroup with hypoplastic bone marrow, the classification according to FAB criteria revealed 28 patients with RA (66.7%), three with RARS (7.1%), and eight with RAEB (19.0%), as well as one patient each with RAEB-T and CMMol (2.4% each), and one case which had to be reckoned among the category of unclassifiable MDS (2.4%). Median survival was 21.8 months for hypoplastic MDS, 26.9 months for normoplastic MDS, and 14.2 months for hyperplastic MDS. During follow-up, 14 patients (33%) with hypoplastic MDS developed acute nonlymphatic leukemia. Although not a constant finding, karyotype abnormalities involving particularly chromosome 7 seem to be associated with hypoplastic MDS. The results confirm the existence of a hypoplastic variant of MDS which seems to more frequently affect female patients, and which requires bone marrow biopsy for its accurate diagnosis.

SUMMARY A 74 year old woman presented with a primary subglottic tumour. Neither cutaneous mastocytosis (urticaria pigmentosa) nor spread to the bone marrow, liver, or spleen were detected. About two years after initial manifestation of the tumour nodular skin metastases appeared, as well as local recurrence in the larynx. Despite chemotherapy and radiation the disease progressed and was fatal. The terminal phase was characterised by generalisation of the mast cell tumour with diffuse infiltration of bone marrow and, shortly before death, leukaemic transformation. The patient died four years after onset of disease with symptoms of a hemorrhagic diathesis. As far as we know this is the first case of mast cell sarcoma to be reported in man.

It was found in the experiments to be described that many steroids in the androstane series profoundly retard the growth of a transplanted benign mammary tumor in adult intact female rats. This paper is concerned with the relationship of the molecular structure of these steroids to their inhibitory effects on the tumor and with mechanisms involved in the depression of neoplastic growth by these agents. A quantitative relationship was found to exist between the dosage of the steroid administered and the extent of the restraint of the tumor which ensued. In the variations of its growth rate in response to hormonal modifications the benign tumor of the rat resembles some human mammary carcinomas, and in this regard it is a serviceable laboratory model that is unique at the present time. The growth of the transplanted tumor is accelerated or retarded by hormones which already have been found through clinical practice to have like effects on carcinoma of the breast of the human being. The availability of quantitative methods of study of a hormone-responsive experimental tumors expands the scope of investigation of mammary neoplasms.The mammary fibroadenoma employed in the experiments has two outstanding characteristics. It is a neoplasm. Secondly, the tumor possesses some of the responsiveness to hormones which is characteristic of normal mammary epithelium of the rat in so far as its growth rate is profoundly altered by the administration or withdrawal of appropriate hormones. With respect to the promotion of growth by steroid and protein hormones, it was shown earlier (1) that there are many similarities in the reactivity of both the transplanted

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