Duration of fungal culture incubation in an area endemic for Histoplasma capsulatum.

To determine the optimum incubation period for recovery of fungi from clinical specimens in an area where Histoplasma capsulatum is endemic, we reviewed the results of 4259 consecutive fungal cultures. Of the total 1306 fungi isolated, 92.6% were detected by day 7, and 97.9% were detected by day 14. For the 1027 yeast isolates, only 1.4% were detected after day 7, none of which was considered clinically significant. Of the 281 mould isolates, 91.1% were detected by day 14; and of those detected after day 14, only isolates of H. capsulatum were considered clinically significant. An incubation protocol based on type of specimen is suggested.

Penicillium peritonitis in a patient receiving continuous ambulatory peritoneal dialysis.

We describe herein a case of peritonitis caused by Penicillium species in a patient receiving continuous ambulatory peritonal dialysis (CAPD). This is the first reported case of Penicillium peritonitis complicating CAPD. It is also unusual because Penicillium typically is considered a contaminant and only rarely is it considered a human pathogen.

Persistence of rickettsiae in the partially viable gangrenous margins of amputated extremities 5 to 7 weeks after onset of Rocky Mountain spotted fever.

A case of Rocky Mountain spotted fever complicated by gangrene of the extremities required amputation and showed persistent rickettsial infection in the margins of the gangrene at 5 and 7 weeks after onset of illness. Rickettsial organisms were demonstrated by immunoperoxidase staining in the viable endothelial cells in the ischemic margins of the gangrenous tissue. We conclude that the cellular, humoral, and pharmacologic components that lead to eradication of the rickettsiae were not delivered to the ischemic margins at effective antirickettsial concentrations.

Oncogene expression and microvessel count in recurrent and nonrecurrent stage Ib squamous cell carcinoma of the cervix.

OBJECTIVE: To evaluate p53, epidermal growth factor receptor (EGFR) and c-erbB-2 oncogene expression and compare it with microvessel count (MVC) in determining the clinical outcome of stage Ib squamous cell carcinoma (SCC) of the cervix. STUDY DESIGN: Immunostaining with p53, EGFR, C-erbB-2 and factor VIII antibodies was performed on tumor sections from 22 patients (11 with cancer recurrence, 11 free of cancer after four years). The levels of oncogene expression were semiquantitatively graded (0-4). Microvessels were counted (per 200 x field) in areas of highest neovascularization. RESULTS: Eight of 11 patients (72.7%) with recurrence expressed EGFR as compared with 5 of 11 patients (45.5%) free of disease. This difference is not significant (P = .39). An equal number of patients with and without recurrence expressed c-erbB-2. Five of 11 patients (45.5%) with recurrence expressed p53, as compared with 6 of 11 (54.5%) free of disease (P = 1.00). Eight of 11 patients (72.7%) with recurrence had an MVC above 24 as compared with 2 of 11 patients (18.2%) free of disease; this difference was statistically significant (P = .03). CONCLUSION: The expression of EGFR, p53 and c-erbB-2 appears to have little prognostic value in stage Ib SCC of the uterine cervix. The prognostic value of MVC is in keeping with previous findings.

Gastro-intestinal stromal tumours (GISTs): a six year Zimbabwean experience. Cellular differentiation with immunocytochemistry.

OBJECTIVES: To determine the prevalence of GISTs in general, the terminology in use, biological behaviour in terms of benign, borderline and malignant variants and assessment of the different lines of differentiation using immunochemical techniques. DESIGN: A retrospective study. SETTING: Department of Histopathology, University of Zimbabwe Medical School at Parirenyatwa and Harare Central teaching Hospitals. SUBJECTS: Patients with a surgical pathology diagnosis of gastro-intestinal related stromal tumours including leiomyosarcomas, leiomyomas and GISTs over a six year period. MAIN OUTCOME MEASURE: Evaluation for different lines of differentiation and malignant potential using immunocytochemical techniques. RESULTS: A total of 24 cases with a primary diagnosis of GISTs over a period of six years were retrieved from the records and of these 22 had material available for evaluation. Four of these were reported as pure GISTs, two of them benign and the other two malignant. Seven cases were reported as leiomyosarcomas. Six of these had evidence of neural differentiation on immunocytochemistry and therefore were strictly not leiomyosarcomas. Of the 11 cases reported as leiomyomas, four (36.4%) had neural differentiation on immunohistochemistry implying a low malignant potential. CONCLUSION: GISTs are not uncommon in this patient population considering that 24 cases were reported over a six year period in a department that averages 11,000 surgical pathology cases per year. Minimal use of immunostains, in addition to general morphological features, can be utilized to determine the line of cellular differentiation and malignant potential of the seemingly benign tumours.

Use of combining in situ hybridization and immunohistochemistry in detecting human papillomavirus on routine sections in cases of diagnostic uncertainty.

OBJECTIVES: To determine the combined role of in situ hybridization (ISH) and immunohistochemistry (IHC) in the detection of human papilloma virus (HPV) infection in cases of diagnostic uncertainty. DESIGN: A retrospective study. SETTINGS: Department of Histopathology at the University of Zimbabwe and Department of Pathology at the University of Texas Medical Branch at Galveston in Texas, both teaching referral hospitals. SUBJECTS: 23 patients with a diagnosis suggestive but not diagnostic of HPV infection on routine histology sections of uterine cervical biopsies, in which 20 had enough material to complete the study. MAIN OUTCOME MEASURES: Surgical pathology records of cases with morphologic features suggestive but not diagnostic of HPV cases were identified. Representative sections of each case were investigated with ISH and IHC for HPV infection. RESULTS: HPV DNA was detected in 12 cases. The bovine papilloma virus (BPV) antibody immunoreacted with six of the cases and two of these had not been detected by ISH resulting in a combined ISH and IHC, HPV detection of 14 cases. CONCLUSION: This preliminary data seems to support the validity of combining IHC and ISH, even though IHC is less sensitive compared to ISH, it may detect certain HPV types not represented in the DNA probe.

Pulmonary malakoplakia in acquired immunodeficiency syndrome: an ultrastructural study of morphogenesis of Michaelis-Gutmann bodies.

Malakoplakia is an unusual inflammatory reaction to a variety of infections, characterized by the accumulation of macrophages containing the target-like calcospherites, the Michaelis-Gutmann body (MGB). We report three patients with acquired immunodeficiency syndrome with pulmonary malakoplakia associated with Rhodococcus equi infection; two patients were diagnosed at autopsy and one by examination of a transbronchial biopsy specimen. All three patients had pulmonary bacterial cultures and light and electron microscopic examination. The patients were 33-, 41-, and 43-year old men, human immunodeficiency virus-positive for 2, 6, 8 years, respectively. The two patients diagnosed at autopsy had cavitary lesions, and the patient diagnosed by biopsy specimen had nodular lesions on chest radiographs. Histologically, the lungs had well-circumscribed areas of infiltration with benign macrophages with granular cytoplasm, scattered MGBs, and numerous gram-positive coccobacilli. Electron microscopic examination showed intracellular coccobacilli, from 990 X 702 to 972 X 648 nm in diameter, with thick, homogenous cell walls, trilaminar cytoplasmic membranes, and dense cytoplasm with from one to five vacuoles. Electron microscopic studies showed that the bacteria within the pulmonary macrophages had thicker cell walls, less prominent nucleoid areas, and more vacuoles than the bacteria in cultures from the sputum and blood. The mature MGB ultrastructurally had a concentric, trilaminate structure with central mineralized core and was without recognizable bacterial forms. Early MGBs, however, consisted of a circular, electron-dense core containing bacteria, ultrastructurally similar to the R. equi seen in the culture. Pulmonary malakoplakia in patients with the acquired immunodeficiency syndrome might thus represent an acquired macrophage dysfunction of the intracellular digestion of phagocytized bacteria. The bacteria within the macrophages, however, seemed to have thicker cell walls compared with those in culture, and thus might be protected from enzyme digestion. It seems that MGBs are formed around the undigested bacteria as an alternative pathway for bacterial destruction, because R. equi was identified within the cores of early MGBs but not the mature or late stage MGBs.