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The present study illustrates characteristic features of histopathology in the 3 non-leukemic, Ph-negative groups of chronic myeloproliferative diseases (CMPD). Attention is paid to the final outcome of CMPD, especially its transformation into acute leukemias and the occurrence of myelofibrosis from bone marrow biopsies (BMB) in a total of 1,716 CMPD patients. Essential thrombocythemia (ET), polycythemia vera (P. vera), and chronic megakaryocytic granulocytic myelosis (CMGM) can readily be distinguished by histopathology from BMB in the great majority of patients without regarding laboratory data, leaving a compartment of about 12% unclassifiable cases. Histologic patterns of staging are the increase in number and pleomorphism of megakaryocytes (MK), increase in number and density of reticulin fibers and collagen fibrosis, and excess of blasts. These 3 criteria are each graded from 0 to 3 in every biopsy. From these, a staging results by means of the histology of BMB in each of the Ph-negative CMPD. This staging provides a classification by defined criteria which permits comparative studies, the possibility of monitoring the individual patients by follow-up histology, and offers a baseline for reliable evaluation of results from therapy protocols.

Interlaboratory variation in human epidermal growth factor receptor 2 (HER2) testing provides a challenge for targeted therapy in breast and gastric cancer. Assessment of positivity rates among laboratories could help monitor their performance and define reference values for positivity rates to be expected in a geographic region. Pathologists regularly determined the number of HER2-positive cases (HER2 3+, HER2 2+/amplified or amplified) in their laboratory, and figures were continuously entered into a central website. The overall positivity rate of each participant was calculated and compared with the average rates of all other institutes (n = 42). A total of 18,081 test results on breast cancer and 982 on gastric cancer were entered into the system. Positivity rates for HER2 in breast cancer ranged from 7.6% to 31.6%. Statistically, the results from six institutions qualified as outliers (p < 0.000005). From the remaining institutions encompassing 10,916 assessments, the mean proportion of positive cases was 16.7 ± 3.2% (99% confidence interval 16.6–16.8). The results from six institutions were in between the 95% and 99.5% confidence intervals. For gastric cancer, there was one outlier and the mean positivity rate was 23.2 ± 5.7%. The proportion of HER2-positive breast cancer cases is considerably lower than could have been expected from published studies. By assessing the positivity rates and comparing them with that of all breast or gastric cancers in a given population, pathologists will be alerted to a potential systematic error in their laboratory assay, causative for over- or underestimation of cancer cases suited for anti-HER2 therapy.

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.

Although the new World Health Organization (WHO) classification acknowledges "prefibrotic" phases, progression of myelofibrosis in chronic idiopathic myelofibrosis (cIMF) is controversial because there are only a few studies about sequential biopsy specimens, and they yield conflicting results. The conflicting results might be due to a mixture of different degrees of myelofibrosis and therapy regimens within the respective groups studied. To prove this hypothesis, we studied sequential bone marrow biopsy specimens from patients with cIMF and compared 3 groups with different degrees of myelofibrosis at initial diagnosis with a group of patients with primarily unfibrosed disease who met the WHO criteria for prefibrotic cIMF. Patients receiving chemotherapy were considered separately from patients without treatment. Our results favor a steady progression of myelofibrosis unrelated to therapy modalities, whereas confusing literature data can be explained: fibrosis may remain static or lessen, especially in more advanced stages of cIMF.

In a retrospective study of 352 patients with primary myelodysplastic syndromes, 61 (17.3%) revealed myelofibrosis in bone marrow biopsies. The fibrosis was observed to occur mostly focally (41/61 cases), and collagen deposits were found very rarely (4/61). The histopathology of bone marrow biopsies revealed hyperplasia and disturbed differentiation in megakaryopoiesis; the frequency and grade of dysplasia in megakaryopoiesis increased with advancing myelofibrosis. Reticulin fibrosis occurred in all subtypes of MDS; however, there was a higher incidence in chronic myelo‐monocytic leukaemia (CMMoL). The frequency of cytogenetic aberrations was significantly higher in the MDS cases with myelofibrosis, compared to the cases without fibrosis. Clinical data showed significantly lower values of haemoglobin and lower platelet counts in MDS with myelofibrosis. Life expectancy was reduced to 9.6 months, compared with 17.4 months in MDS without fibrosis. In refractory anaemia, the survival times were 10.0 months in MDS with myelofibrosis, compared to 28.9 months in MDS without myelofibrosis. 36.6% of the patients with MDS and myelofibrosis developed a transformation into ANLL during the course of the disease. Myelofibrosis therefore seems to herald a poor prognosis.

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