Malignant fibrous histiocytoma and malignant melanoma: the role of immunohistochemistry and electron microscopy in the differential diagnosis.

Malignant fibrous histiocytoma (MFH) and malignant melanoma (MM) occur together often in the differential diagnosis of poorly differentiated neoplasms. They differ, however, in their biologic behavior and recommended treatment. Investigators have therefore explored a variety of special techniques, including electron microscopy (EM) and immunoperoxidase (IP), to classify these tumors accurately and to separate them from each other. To determine the usefulness of IP and EM in the classification of these tumors, we applied a Fontana-Masson stain and IP probes for vimentin, alpha-1-antitrypsin (alpha-1-A), human melanoma black (HMB)-45, and S-100 protein to twelve MMs and nine MFHs, all of which had available EM studies. Three of twelve MMs were amelanotic. All tumors contained vimentin. Eight of twelve MMs and six of nine MFHs contained alpha-1-A. Ten of twelve MMs and no MFHs contained HMB-45. Eleven of twelve MMs and, surprisingly, two of nine tumors classified by light and EM as MFHs contained S-100 protein. When problems arose with either IP negativity or potentially misleading cross-reactivity, careful EM study allowed definitive classification.

Granulocytic fragments in sepsis.

We report here three patients with sepsis and one with acute pancreatitis and possible sepsis who developed granulocytic fragments on blood smears obtained prior to death. In case 1, these fragments were identified cytochemically. In case 3, granulocytic cytoplasmic projections and fragments were identified by electron microscopy of the buffy coat. All patients had leukerythroblastosis. The average corrected white blood count (WBC) was 46 X 10(9)/liter with 34 nucleated red blood cells (nRBC)/100 WBC. Patient 1 had thrombocytosis whereas patients 2, 3, and 4 were thrombocytopenic. Terminal complement levels were decreased in patients 3 and 4 as previously noted in sepsis (Sprung CL, Shultz DR, Marcial E, et al.: Complement activation in septic shock patients. Crit Care Med 14:525, 1986). A general correlation between nRBC and granulocytic fragments/100 hpf (high power field) was observed in patients 3 and 4. Granulocytic fragments were not identified on the blood smears of several patients with leukemoid reactions without erythroblastosis. Although the precise etiology of these fragments is unclear, we believe their recognition is important because all patients died within 32 hours after granulocytic fragments were identified. Furthermore, these fragments can falsely elevate the platelet count. Although myeloid fragments have previously been noted in leukemia and lymphoma, this is the first report of their association with conditions unrelated to hematologic neoplasms. These fragments can easily be recognized by careful examination of the blood smear and represent a newly recognized aspect of the septic shock syndrome.

An ultrastructural and light microscopic study of the synovium in ochronotic arthropathy.

The synovium in two well-documented cases of alkaptonuric ochronosis was studied by transmission electron and light microscopy. A feature of alkaptonuria previously unreported in the English-language literature was the presence of phagocytosis of large collagen fibrils by synovial macrophages in both cases. The origin of these fibrils appeared to have been shards of ochronotic cartilage and areas of metaplastic cartilage. This finding suggests that active remodeling of the synovial tissues occurs in advanced ochronotic arthropathy. Numerous shards of ochronotic cartilage were embedded in the synovium. In addition, small aggregates of large collagen fibrils encrusted with apparent ochronotic pigment were occasionally noted in the interstitium. These aggregates of ochronotic collagen are best described as microshards, and they have not generally been recognized in the literature. What appeared by light microscopy to represent ochronotic pigment deposition in interstitial collagen actually represented embedded microshards of ochronotic cartilage in the interstitium. Slender and elongated microshards were most likely to be confused by light microscopy as ochronotic interstitial collagen.

Effect of carbon source on enzymes involved in glycerol metabolism in Neurospora crassa.

Specific activities of eight enzymes involved in glycerol metabolism were determined in crude extracts of three strains of Neurospora crassa after growth on six different carbon sources. One of the strains was wild type, which grew poorly on glycerol as sole carbon source; the other two were mutant strains which were efficient glycerol utilizers. A possible basis for this greater efficiency of glycerol utilization was catabolite repression of glyceraldehyde kinase by glycerol in wild type, and two-fold higher glycerate kinase activity in the mutant strains after growth on glycerol, thus apparently allowing two routes for glyceraldehyde to enter the glycolytic pathway in the mutant strains but only one in wild type. The preferential entry of glyceraldehyde to the glycolytic pathway through glycerate was suggested by the lack of glyceraldehyde kinase in all three strains after growth on one or more of the carbon sources and the generally higher levels of aldehyde dehydrogenase and of glycerate kinase than of glyceraldehyde kinase.