The morphological variants of dermal fibrous histiocytomas have engendered a confusing terminology. One hundred and eighty‐nine cases of fibrous histiocytomas were studied in order to define the morphological spectrum exhibited by these lesions.
Based on the prevailing morphological components, fibrocollagenous, vascular, or histiocytie. an arbitrary division into three main categories was made. A fourth group was defined to include those cases in which a fully developed storiform pattern was the dominant morphological feature. The majority (115 cases) of the lesions were of the fibrocollagenous variety. Lesions with an angiomatous component (vascular variety) were the next most common (41 cases). Thirteen of the tumors were of the histiocytic variety.
Twenty tumors were of the storiform variety and fulfilled many of the microscopic criteria of dermatofibrosarcoma protuberans. This latter group often presents a diagnostic problem and may stimulate fibrosarcoma, aggressive fibromatosis or other connective tissue neoplasias. The combination of several clinical and pathological features are helpful in better separating this variety from the more benign forms.
The presence of different well‐defined morphological components developing in the same tumors suggests a common origin.
A conventional histopathological and quantitative morphometric study of 28 capsulated peripheral and spinal nerve benign schwannomas demonstrated linear and parabolic correlation between Antoni B tissue, vascularity and tumour size. The results support the endoneural connective tissue origin of Antoni B, and suggest a model of tumor growth that is partially limited by the growth potential of the Antoni B and/or the vascular component.
We report a case of right intrathoracic kidney associated with a complex somite malformation that comprised vertebral fusion and right intrathoracic supernumerary ribs. The interpretation of this association as a disease model of nature allows us to propose a unifying hypothesis on the pathogenesis of this form of renal dystopia.
The specialized conducting systems of 44 hearts with posterior-inferior acute myocardial infarction were studied to clarify the anatomic basis of atrioventricular (AV) block. The results showed a lack of correlation between the block and the lesional pathology of the specialized conducting system. On the other hand, an evaluation of the atrial prenodal myocardium revealed strong clinicopathologic correlation between the block and the necrotic damage to these fibers. Twenty-nine or 97% of patients with AV block showed acute necrosis of the prenodal atrial myocardium. Considering the conducting prenodal septal atrial myocardium as a suprahisian structure, the necrosis at this level would provide an anatomic basis of the block in posterior-inferior acute myocardial infarction. Analysis of the behavior of the AV block after pharmacologic treatment further established a relationship between the block and acute lesions in the central conduction system. Circulation 75, No. 4, 733-736, 1987. BETWEEN a fifth and a third of all patients suffering posterior acute myocardial infarction (P-AMI) develop grade II to III atrioventricular (AV) block.'`2 In the majority of patients surviving the acute phase, the block is generally transient and its prognostic significance is variable and rarely grave.3Most electrophysiologic studies favor a suprahisian origin of the AV block in P-AMI.24'5 However, the block has also been ascribed to the His bundle level.6 Although clinical and electrophysiologic studies generally agree on the transient nature and suprahisian location of the block, the anatomic basis of the electrical disturbance remains a matter of controversy.2 Nonanatomic mechanisms have also been advocated to explain the AV conducting disturbance. Likewise, temporal hypoxia,1 cholinergic reflexes,3 and a local increase in extracellular hyperkalemia have been implicated in the genesis of the block.7The anatomic basis of the block may be hidden in topographic sites not previously studied in this con- text, such as the conducting septal prenodal atrial myocardium. In this morphologic study we sought to clarify the anatomic basis of the AV block in P-AMI.
Materials and methodsWe studied the hearts of 44 patients with P-AMI. A grade III AV block was recorded in 26 cases and grade II block was found in four.Routine histopathologic examination of the infarcts included postmortem coronary angiography and step sectioning of the coronary arteries. Camera lucida drawings were obtained from four tetrazolium hydrochloride-stained, whole heart slices taken at regular intervals from base to apex. Each slice was then further divided into an average of 10 to 12 mapped and numbered sections comprising the entire slice. The sections were stained with hematoxylin and eosin, and the extent of the infarct was then evaluated morphometrically.Study of the specialized AV conducting system and the atrial prenodal myocardium was carried out systematically in all cases. The Koch triangle was cut into eight tissue blocks, as shown in figure 1
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