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Biomedical subjects

A H Dachman

Publications and source records attributed to A H Dachman.

At least 55 records · Page 3Linked to original sources
PubMed1987

Mesenteric and omental cysts: histologic classification with imaging correlation.

Forty-one cases of mesenteric and omental cysts are reported. Histologically, several specific types could be distinguished: lymphangioma, 19 cases; nonpancreatic pseudocyst, 11 cases; enteric duplication cyst, six cases; mesothelial cyst, three cases; and enteric cyst, two cases. A lymphangioma is usually a multiloculated cyst located in the mesentery that shows no discernible wall on computed tomography (CT) and may have characteristics of fat on CT and magnetic resonance imaging. Abnormalities in the small bowel mucosa were frequently noted on barium studies. A nonpancreatic pseudocyst is usually a unilocular or multilocular cyst located in either the mesentery or the omentum, with abundant debris sonographically and an enhancing wall on CT. An enteric duplication cyst is a unilocular cyst with an enhancing wall on CT. Mesothelial and enteric cysts are anechoic, thin-walled cysts. Emphasis is placed on the importance of identifying lymphangioma, which is more difficult to manage than the other forms of mesenteric and omental cysts.

Adult↗
PubMed1987

Natural history of the obstructed rabbit appendix: observations with radiography, sonography, and CT.

Chronic (1-3 months' duration) appendiceal obstruction was induced in 11 rabbits to assess the pathologic consequences and to study the associated radiologic, sonographic, and CT findings. Three pathologic/radiologic groups resulted with approximately equal frequency. In group A, the abscess was characterized by inflammatory cells in the lumen and wall of the appendix without mucin production. Calcification was shown radiographically, and sonography showed an anechoic or complex pattern. Group B, the "mixed response," was characterized by an intact hyperplastic mucosa, mucin secretion, and inflammatory debris in the lumen. Occasional calcification was present radiographically, and sonography showed a complex or hypoechoic pattern. In group C, true mucoceles had an intact hyperplastic mucosa, a mucin-filled lumen, and minimal inflammation. These were anechoic on sonography except for mobile foci of inflammatory debris. Chronic obstruction of the appendix results in a spectrum of pathologic responses with varying degrees of either inflammation and mucosal destruction or mucosal hyperplasia and mucin secretion. An abscess results when infection overwhelms the host's inflammatory responses. If the bacteria are destroyed by these defenses, a mucocele forms. An intermediate situation occurs when there is a mixed response with chronic inflammatory changes and an intact mucosa. This finding supports the existence of chronic appendicitis in humans.

Animals↗
PubMed1987

Nodular regenerative hyperplasia of the liver: clinical and radiologic observations.

This report describes 21 cases of nodular regenerative hyperplasia (NRH) and its clinical and radiologic features. NRH of the liver is an established pathologic entity that should not be confused with focal nodular hyperplasia, hepatocellular adenoma, or the regenerative nodules associated with cirrhosis. Correct diagnosis will prevent an unnecessary hepatic lobectomy should NRH be mistaken for hepatocellular adenoma. Unlike focal nodular hyperplasia, NRH may bleed, may be associated with portal hypertension in one-half of cases, and is often associated with a systemic disease such as a myelo- or lymphoproliferative disorder. Correct diagnosis is important because the prognosis in patients with NRH and portal hypertension is better than that in patients with portal hypertension due to cirrhosis. Radiologically, multiple nodules, large masses, or an apparently normal liver (containing nodules less than 0.5 cm in diameter) were visible. The nodules may take up technetium sulfur colloid and have variable echogenicity on sonography. They are often hypodense on CT without significant enhancement. The nodules may fill from the periphery on angiography, are vascular, and sometimes contain small hypovascular areas due to hemorrhage. A large nodule may rupture and cause hemoperitoneum. These findings may resemble some features of focal nodular hyperplasia, hepatocellular adenoma, or metastases. NRH is probably underdiagnosed owing to a lack of recognition of the entity and limited sampling of liver tissue by needle biopsy. Scintigraphy, sonography, and CT of the liver should be performed in cases of idiopathic portal hypertension to detect NRH. In cases with compatible findings, multiple needle biopsies or a laparoscopically guided needle biopsy or wedge liver biopsy should be recommended for definitive diagnosis.

Adenoma↗
PubMed1986

Mesenchymal hamartoma of the liver: radiologic-pathologic correlation.

Mesenchymal hamartoma of the liver (MHL) is an uncommon cystic mass of infancy that is a developmental anomaly rather than a neoplasm. Fourteen cases of MHL were retrospectively reviewed. Grossly, MHL is a solitary mass with cystic spaces of variable size. Patients are seen initially with painless progressive abdominal enlargement. On plain films, MHL appears as a large, noncalcified mass in the right upper quadrant. Scintigraphy is helpful in confirming its hepatic origin. Ultrasonography and computed tomography demonstrate a large multiloculated mass with considerable variation in the size of septa and cystic spaces. Angiographically, MHL is avascular or hypovascular. Recognition of these radiographic findings allows a correct diagnosis to be made in many cases. With resection, the prognosis is excellent.

Angiography↗
PubMed1986

Undifferentiated (embryonal) sarcoma of the liver: radiologic-pathologic correlation.

Undifferentiated (embryonal) sarcoma (UES) is an uncommon malignant mesenchymal hepatic tumor that occurs in older children and young adults. Fourteen cases are correlated with radiologic and pathologic findings. Radiologic findings reflect the spectrum of solid to cystic appearances observed in the gross specimens. Sonography typically demonstrates a large mass that may be predominantly solid with many small anechoic spaces or may be cystic. Computed tomography reveals a hypodense mass with hyperdense septa of variable thickness and a dense peripheral rim corresponding to the fibrous pseudocapsule of the tumor. Angiographically, UES is usually hypovascular with tumoral vessels, although hypervascular and avascular patterns occur. Prognosis of UES is poor, with a median survival of less than 1 year. Radiologists should be familiar with this malignant tumor since it may present as a large cystic hepatic mass, suggestive of a benign lesion.

Adolescent↗
PubMed1986

Nonparasitic splenic cysts: a report of 52 cases with radiologic-pathologic correlation.

We reviewed 52 cases of splenic cysts on file at the Armed Forces Institute of Pathology. There were 24 true (epidermoid) and 28 false (posttraumatic) cysts. The history and clinical presentations, including pain, splenomegaly, or mass, were similar in both groups. Radiologic manifestations included splenomegaly and the occasional identification of a distinct mass by conventional radiography even in the absence of calcification. The lesions produced a photopenic defect on nuclear scintigraphy and were avascular on angiography. Sonography and CT demonstrated a cystic lesion with occasional septations, wall trabeculation, and low-level internal echoes. Three false cysts demonstrated solid and cystic components on sonography and CT, corresponding to organizing hematoma within the cyst. Splenomegaly or a splenic mass of a predominantly cystic nature with no clinical evidence of echinococcus suggests the diagnosis of splenic cyst. Reliable radiologic distinction between true or false splenic cyst does not seem possible. Complex mass may represent a "transition" between hematoma and false splenic cyst.

Adolescent↗
PubMed1985

Normal erect swallowing. Normal function and incidence of variations.

Of 871 candidates presenting for upper gastrointestinal examinations, 16 met the rigorous criteria established for selecting asymptomatic normal volunteers. Frame-by-frame evaluation of their videorecorded pharyngeal swallow confirmed many observations made previously utilizing cine recording at much higher radiation dosages. In addition, new observations were made: the nasopharynx may not occlude until the bolus is entirely within the pharynx; air mixes with the bolus if the swallow is an "open" type; the epiglottis always inverts in normal individuals regardless of the type of swallow ("open," air filled oro-and hypopharynx into which the swallowed bolus is dropped; "closed," airless oropharynx into which the swallowed bolus is pushed by a continuous peristaltic drive of the tongue and palate, thus reconstituting the pharyngeal space); laryngeal descent may aid in stripping the bolus from the pharynx; the vestibule may not completely close during the swallow and the larynx can still be impervious to the bolus; the peristaltic wave does not begin until the bolus has breeched the cricopharyngeus; the cricopharyngeus may be seen frequently in normal individuals, but does not delay the passage of the bolus; asymmetric flow of the bolus around the larynx is common and may not be the result of epiglottic tilt or head positioning.

Adolescent↗
PubMed1985

Solid and papillary epithelial neoplasm of the pancreas.

Solid and papillary epithelial neoplasm of the pancreas is an uncommon low grade malignant tumor histologically distinct from the usual ductal adenocarcinoma and amenable to cure by surgical excision. It tends to occur in black women in their second or third decade of life and has often been misclassified as nonfunctional islet cell tumor or as cystadenoma or cystadenocarcinoma. Twelve cases were reviewed. Sonography and CT of solid and papillary epithelial neoplasms depict a well-demarcated mass that can be solid, mixed cystic and solid, or largely cystic. The radiologic appearance is dependent on the maintenance of the integrity of the neoplasm versus the extent of retrogressive changes that have occurred.

Adolescent↗
PubMed1985

Fibrolamellar hepatocellular carcinoma.

Fibrolamellar hepatocellular carcinoma (HCC) has recently been separated as a distinct clinicopathologic entity with a better prognosis than the usual HCC associated with cirrhosis. The mean age of our 17 patients was 20 years. Alpha fetoprotein levels were normal, and none of the risk factors for HCC was present. Distinctive histologic features included deeply eosinophilic polygonal hepatocytes and abundant fibrous stroma. Calcification was present on plain films of five of 13 cases. Sonography usually showed a homogeneous, echogenic mass. Computed tomography (CT) demonstrated small, central calcification in four of ten cases. A central echodensity, hypodense on CT scans, was seen in two cases and corresponded to a central scar. By combining clinical and laboratory data with radiologic tests, a correct diagnosis can often be suggested before biopsy is performed.

Adolescent↗
PubMed1985

Mucocele of the appendix and pseudomyxoma peritonei.

Mucocele of the appendix is a descriptive term for an abnormal mucous accumulation distending the appendiceal lumen. Pseudomyxoma peritonei is characterized by mucinous ascites and implants throughout the abdominal cavity. Thirty-four cases of appendiceal mucocele and seven cases of pseudomyxoma peritonei of appendiceal origin on file at the Armed Forces Institute of Pathology were reviewed for their clinical, pathologic, and radiologic findings. These cases provided examples of the major radiologic findings reported in this entity. Previously unreported findings of dependent echoes within some mucoceles on sonography and pseudomyxoma peritonei tracking along the umbilical vein remnant or mimicking an intrahepatic mass are presented.

Adenocarcinoma↗
PubMed1983

Cystic neoplasms of the pancreas. Radiological-pathological correlation.

Microcystic adenomas and mucinous cystic neoplasms of the pancreas have often been described interchangeably (cystadenoma, cystadenocarcinoma), causing confusion with respect to their radiographic characteristics. The former are composed of innumerable tiny cysts and are benign, whereas the latter contain large, unilocular or multilocular cysts, sometimes with shaggy excrescences, and are either frankly or potentially malignant. Microcystic adenomas are angiographically hypervascular and may have central calcification. Sonographically, they have a mixed hypoechoic and echogenic pattern, while CT numbers reflect a mixture of connective tissue and proteinaceous fluid and contrast enhancement is seen. Mucinous cystic neoplasms are hypovascular and may have peripheral calcification; ultrasound and CT reflect their predominantly cystic character and demonstrate excrescences when present.

Adult↗
PubMedDate not supplied

Colorectal carcinoma in young patients: CT detection of an atypical pattern of recurrence.

Colonic adenocarcinoma is an uncommon but aggressive neoplasm in patients under the age of 40. The goals of this study were to evaluate the utility of computed tomography (CT) in preoperative staging and detection of postoperative recurrences in young patients with colon cancer and to evaluate the pattern of recurrent disease. We reviewed 51 cases of adenocarcinoma in patients aged 40 years and younger. CT preoperatively staged 21 (72%) of 29 patients correctly and had a 100% positive predictive value for metastatic disease. Recurrent disease occurred in 23 (76%) of 30 nonstage D patients with at least 2 years of disease-free follow-up. CT accurately detected 21 (91%) of 23 cases of recurrent disease. Local recurrences were detected in 20 (87%) of 23 patients. Isolated local disease was the most frequent pattern of recurrence, seen in 17 (74%) of 23 patients. Hepatic metastases were rare and occurred in nine (13%) of 51 patients. Young patients with colon cancer have an increased prevalence of isolated local recurrences and decreased rate of hepatic metastases than the older population. In order to detect early, and therefore resectable recurrent disease, CT examinations should be obtained early and often in the postoperative period.

Adenocarcinoma↗
PubMedDate not supplied

Diagnostic performance of virtual colonoscopy.

The most important diagnostic performance of virtual colonoscopy is the ability to detect colorectal polyps. However, its diagnostic value for evaluation of patients undergoing incomplete colonoscopy and the ability to detect unsuspected extracolonic findings are also important diagnostic features. Because of important differences between published patient populations, a meta-analysis combining data from different studies would not provide a reliable statistic. The by-patient sensitivity for patients with polyps 10 mm and larger ranges from 75% to 100% in most series and was 100% in the two largest series published to date. By-polyp sensitivity for polyps 10 mm and larger ranges from 50% to 100% and was 89-90% in the two largest series. Detailed data on smaller polyps are summarized. Virtual colonoscopy is an excellent test for evaluation of patients with incomplete colonoscopies. The incidence of significant extracolonic findings is 7-13%.

Colon↗
PubMedDate not supplied

CAD techniques, challenges, and controversies in computed tomographic colonography.

Computer-aided diagnosis (CAD) for computed tomographic colonography (CTC) automatically detects the locations of suspicious polyps and masses on CTC and provides radiologists with a second opinion. CAD has the potential to increase radiologists' diagnostic performance in the detection of polyps and masses and to decrease variability of the diagnostic accuracy among readers without significantly increasing the reading time. Technical developments have advanced CAD substantially during the past several years, and a fundamental scheme for the detection of polyps has been established. The most recent CAD systems based on this scheme produce a clinically acceptable high sensitivity and a low false-positive rate. However, CAD for CTC is still under active development, and the technology needs to be improved further. This report describes the expected benefits, the current fundamental scheme, the key techniques used for detection of polyps and masses on CTC, the current detection performance, as well as the pitfalls, challenges, controversies, and the future of CAD.

Colonic Polyps↗