Follicular mantle zone cell subpopulations detected by monoclonal antibody SN3

The CD24hi smooth muscle subpopulation is the predominant fraction in uterine fibroids

Uterine fibroids are the most common gynecological tumors affecting women in their reproductive age. Despite this high incidence the pathogenesis of fibroids is widely unsolved. Whereas formerly only imbalances in hormonal levels were considered to account for tumor development, the identification of genetic changes likely to affect myometrial stem cell reservoirs provided a novel approach to fibroid genesis. Here, we identified a certain subset of cells by the surface marker CD24 with increased abundance in fibroids compared with myometrial tissue. Fibroid cells expressing CD24 shared certain features of immature or progenitor-like cells such as quiescence, reduced expression of smooth muscle differentiation markers and elevated expression of genes involved in the wingless-type (WNT)-pathway such as beta-catenin. In addition, a positive correlation between CD24 and wingless-type family member 4 (WNT4) expression was observed in uterine fibroids with mediator subcomplex 12 gene (MED12) mutations. Our findings suggest that cells highly expressing CD24 represent a type of immature smooth muscle progenitor cells. Their accumulation might be driven by disturbed differentiation processes caused by genetic changes possibly involving MED12 mutations or high mobility group AT-hook (HMGA)2 rearrangements.

Acute myelogenous leukemia with leukemia cutis. Eighteen cases seen between 1969 and 1986

Leukemia cutis was documented by biopsy in 18 of 877 patients (2%) with acute myelogenous leukemia (AML) seen at Roswell Park Memorial Institute (Buffalo, NY) between 1969 and 1986. French-American-British (FAB) types included four M2, one M3, ten M4, and three M5. Lysozyme was more consistently detectable in skin sections in our cases than Leu-M1, alpha-1-antitrypsin, alpha-1-antichymotrypsin, or chloroacetate esterase activity. Additional extramedullary sites of involvement were present in 16 patients, including meningeal leukemia in six. Two patients had leukemia cutis preceding bone marrow leukemia. Skin was the initial site of relapse in 11 patients, without marrow relapse, occurring as late as 5.5 years after diagnosis. Most patients in this retrospective series were treated with radiation therapy and/or palliative chemotherapy, and did poorly, with prompt bone marrow relapses and serial skin relapses. Long-term disease-free survival was achieved in the one patient whose skin relapse was treated with whole-body electron-beam radiation therapy in conjunction with reinduction and consolidation chemotherapy. Severe skin toxicity was caused by administration of Adriamycin (doxorubicin) 12 days after electron-beam irradiation in one patient, but was not seen when cytosine arabinoside was administered in doses up to 3 g/m2 in conjunction with radiation therapy. This retrospective review suggests that optimal management of AML involving skin might include whole-body electron-beam irradiation in conjunction with induction or reinduction chemotherapy without anthracyclines, followed by consolidation chemotherapy. Additionally, there should be ongoing surveillance for and treatment of extramedullary disease at other sites, including the meninges.

Splenic marginal zone lymphocytes and related cells in the lymph node: a morphologic and immunohistochemical study

The marginal zone of the spleen contains a well-defined population of lymphocytes with an unknown function. The question is whether this cell population is unique to the spleen or is it also present in the lymph node. These cells have medium-sized nuclei and a moderate amount of cytoplasm. Immunohistochemistry and enzyme histochemistry revealed a marker pattern by which these cells could be distinguished from the lymphocytes of the mantle zone of the spleen: IgD-, CD23-, KiB3-, and alkaline phosphatase+. In the lymph node, the outer side of the follicular mantle contains a subpopulation of B lymphocytes with a similar morphology and the same marker pattern. This subpopulation differs from the marginal zone cells in the spleen in that it does not form a distinct zone. These cells are especially prominent in lymph nodes with fatty atrophy. Their relationship to other subpopulations of B lymphocytes and to malignant lymphomas is evaluated but remains questionable.