Malignant fibrous histiocytoma in bone infarct. Association with sickle cell trait and alcohol abuse.

A 42-year-old black man with sickle cell trait and a history of alcohol abuse had a malignant fibrous histiocytoma of the distal femur. The tumor developed in a bone infarct that had been present for at least 54 months. This is the first reported association of malignant fibrous histiocytoma and bone infarct in which the infarct was related to sickle cell trait and alcohol abuse. A detailed map of the sections from the resected femur disclosed a spectrum of cytologic changes in the sarcoma that ranged from bland fibroblasts in the center of the tumor to high-grade sarcoma at the periphery. Awareness of this spectrum has diagnostic importance regarding the potential underdiagnosis of well-differentiated malignant fibrous histiocytoma.

Angiomatoid carcinoma of the thyroid gland. Anaplastic carcinoma with follicular and medullary features mimicking angiosarcoma.

A 79-year-old man with a 28-year history of a substernal goiter had an anaplastic thyroid neoplasm with prominent angiomatoid features develop. Based on the light microscopic appearance of the tumor and the presence of immunocytochemical staining for Factor VIII-related antigen, a diagnosis of angiosarcoma was made. Subsequent immunocytochemical and ultrastructural studies suggested follicular and medullary differentiation without staining for Ulex europeaus I lectin or evidence of Weibel-Palade bodies. Based on these findings, the tumor is interpreted as an anaplastic carcinoma with evidence of mixed follicular and medullary differentiation and extensive intravascular growth producing an angiomatoid appearance. Positivity for Factor VII-related antigen may be due to nonspecific uptake of antigen-rich serum and platelets by the phagocytic tumor cells. Factor VIII-related antigen immunoreactivity should be interpreted with caution in intravascular neoplasms.

University of Virginia case conference. Macroamylase, macro creatine kinase, and other macroenzymes.

The importance of macroenzymes has become increasingly apparent in recent years (1,2). Macroamylase (EC 3.2.1.1) and macro CK (EC 2.7.3.2) are the macroenzymes most commonly noted in the clinical laboratory, and they are frequently responsible for diagnostic confusion. Several methods are available for the confirmation and analysis of macroenzymes, many of which require expensive equipment or complicated techniques. In this report we summarize two cases of macro creatine kinase and two cases of macroamylase that illustrate the clinical importance of recognizing these macroenzymes. We review the features of these macroenzymes, discuss their laboratory evaluation, and describe a simple method that we have used to detect the macroenzymes in these (and other) patients at our institution. Finally, we review the literature on other, less commonly observed macroenzymes in human blood. We stress (a) the impact of methodology on clinical impressions and (b) the importance of discussing laboratory observations with the patient's physician and communicating them to the patient's medical record in writing.

Optimization and evaluation of cardiac enzymes and isoenzymes measured on a random access analyzer.

Four serum enzymes and isoenzymes used in the diagnosis of acute myocardial infarction (AMI), lactate dehydrogenase LD and LD-1, creatine kinase (CK), and CK-MB have been adapted to the Technicon RA-1000 automated clinical chemistry analyzer. Analytical parameters have been adjusted to provide clinically acceptable precision for all four assays. Correlations with centrifugal analyzer procedures gave correlation coefficients ranging from 0.998 to 0.999. A limited clinical study of the CK-MB assay indicated that a discriminant value of 13 U per L could separate AMI from non-AMI patients.

Retrorectal cystic hamartoma. Report of three cases, including one with a perirenal component.

Retrorectal cystic hamartomas (RCHs) are uncommon lesions of controversial pathogenesis that arise in the presacrococcygeal space. We describe the clinicopathologic features of RCHs from three adult patients. Two were asymptomatic women; the third was a man who had a pelvic abscess. All three specimens were multiloculated cysts lined by squamous, transitional, and glandular epithelium. Poorly organized collections of smooth muscle were present in the surrounding connective tissue, but no well-formed smooth-muscle coat was seen. Although RCHs possess elements of three germ-cell layers, their histologic features are similar to those of the embryonic tailgut. The male patient also had a perirenal mass that was grossly and histologically identical to the RCH. The associated kidney was malrotated. A portion of the embryonic tailgut may have been pulled cephalad by the developing kidney, inhibiting its rotation. Clinicopathologic features distinguish RCH from other retrorectal cystic lesions, including teratoma, dermoid, epidermal cyst, rectal duplication, anal duplication, and anal gland cyst.