Early diagnosis of intravascular large B-cell lymphoma: clues from routine blood smear morphologic findings.

Intravascular large B-cell lymphoma (IVLBCL) is a mature B-cell neoplasm characterized by malignant lymphoid cells within the lumina of blood vessels and capillaries. Given its varied and nonspecific clinical manifestation, this aggressive disease is often not diagnosed until an advanced clinical stage or even at autopsy. This case highlights a patient presenting with autoimmune hemolytic anemia (AIHA) and fevers. Atypical circulating cells on a screening peripheral smear lead to flow cytometric studies highlighting an increase in large, light chain restricted CD20 positive cells. A diagnostic bone marrow biopsy was performed and trephine cores demonstrated predominantly intrasinusoidal lymphoma cells. In conjunction with additional immunophenotypic data, these studies strongly supported a diagnosis of IVLBCL. Judicious use of flow cytometry and morphology resulted in an early-stage diagnosis and likely contributed to the patient's current complete remission status following anti-CD20 therapy. Differential diagnoses for this presentation are discussed in light of serologic, immunophenotypic, histologic, and cytogenetic findings.

Thyroid hormone promotes remodeling of coronary resistance vessels.

Low thyroid hormone (TH) function has been linked to impaired coronary blood flow, reduced density of small arterioles, and heart failure. Nonetheless, little is known about the mechanisms by which THs regulate coronary microvascular remodeling. The current study examined the initial cellular events associated with coronary remodeling induced by triiodothyronine (T3) in hypothyroid rats. Rats with established hypothyroidism, eight weeks after surgical thyroidectomy (TX), were treated with T3 for 36 or 72 hours. The early effects of T3 treatment on coronary microvasculature were examined morphometrically. Gene expression changes in the heart were assessed by quantitative PCR Array. Hypothyroidism resulted in arteriolar atrophy in the left ventricle. T3 treatment rapidly induced small arteriolar muscularization and, within 72 hours, restored arteriolar density to control levels. Total length of the capillary network was not affected by TX or T3 treatment. T3 treatment resulted in the coordinate regulation of Angiopoietin 1 and 2 expression. The response of Angiopoietins was consistent with vessel enlargement. In addition to the well known effects of THs on vasoreactivity, these results suggest that THs may affect function of small resistance arteries by phenotypic remodeling of vascular smooth muscle cells (VSMC).