Microbiologic and clinical characteristics of biofilm-forming Candida parapsilosis isolates associated with fungaemia and their impact on mortality

OBJECTIVES

Biofilm formation (BF) by fungal isolates may dramatically complicate infection. We determined the ability of Candida parapsilosis isolates from single fungaemia episodes to form biofilms and we analysed biofilm subgroups for antifungal susceptibility and pathogenic potential. We then correlated BF with clinical characteristics and outcomes of the episodes.

METHODS

BF was measured using the crystal violet biomass assay. Antifungal susceptibility of preformed biofilms was assessed, and virulence was studied using the Galleria mellonella model. A retrospective analysis of patients' clinical records was performed.

RESULTS

Of 190 patient-unique isolates, 84, 38 and 68 were identified as having high BF (HBF), moderate BF (MBF) or low BF (LBF), respectively. Among 30 randomly selected isolates, nine (eight HBF and one MBF), six (all HBF) and one (HBF) isolates had elevated sessile minimum inhibitory concentrations to fluconazole, anidulafungin or amphotericin B; all HBF and MBF isolates had elevated voriconazole sessile minimum inhibitory concentrations. G. mellonella killing rates of HBF isolates were significantly greater than MBF (or LBF) isolates (50% vs. 20%, 2 days from infection). By comparing HBF/MBF (106 patients) and LBF (84 patients) groups, we found that HBF/MBF patients had more central venous catheter-related fungaemias (62/106 (58.5%) vs. 29/84 (34.5%), p 0.001) and were more likely to die at 30 days from fungaemia onset (61/106 (57.5%) vs. 28/84 (33.3%), p 0.01). In the HBF/MBF group, azole antifungal therapy and central venous catheter removal were significantly associated with a higher and lower 30-day mortality rate, respectively.

CONCLUSIONS

C. parapsilosis BF influences the clinical outcome in patients with fungaemia.

A histological procedure to study fungal infection in the wax moth Galleria mellonella

The invertebrate model Galleria mellonella is a widely used factitious host to study the microbial pathogenesis in vivo. However, a specific procedure for the recovery and the processing of the infected tissues, important for a better understanding of the host-pathogen interactions, has not been reported to our knowledge. In the present study we describe a new procedure of fixation and processing of larval tissue that allows studying the larval topographic anatomy and assessing the morphological changes due to the fungal infection. Lepidopteran larvae were infected with Candida albicans strains displaying various biofilm-forming abilities. The whole larvae were then examined for tissue changes by histological techniques. We show that comparing cutting planes, serial transversal sections of paraffin-embedded larva result in better accuracy and information recovering. Using this technique, it was possible to preserve the integrity of G. mellonella internal structures allowing the detailed analysis of morphological differences in different experimental groups (i.e., healthy vs infected larvae). We were also able to study strain-related differences in the pathogenesis of C. albicans by observing the immune response elicited and the invasiveness of two isolates within the larval tissues. In general, by processing the whole larva and optimizing routinely histochemical stainings, it is possible to visualize and analyse infected tissues. Various degrees of pathogenicity (strain- or inoculum-related), and the infection time course can be described in details. Moreover, the host immune response events can be followed throughout the infectious process leading to a comprehensive picture of the studied phenomenon.

A rare case of transmural endometriosis in primary adenocarcinoma of the rectum

Intestinal endometriosis of the rectum and sigmoid colon, occurring in up to 34% of pelvic endometriosis, mimics a wide number of conditions that are difficult to differentiate from inflammatory or malignant diseases. Herein we report the first case of transmural endometriosis concomitant with advanced primary rectal adenocarcinoma, presenting with obstructive symptoms. Correct diagnosis based on morphological identification and immunohistochemical characterization of the two entities is crucial for treatment.

EGFR overexpression in malignant pleural mesothelioma. An immunohistochemical and molecular study with clinico-pathological correlations

The epidermal growth factor receptor (EGFR) is overexpressed in many epithelial malignancies, against which some antitumoral drugs have been developed. There is a lack of information as to EGFR expression in malignant pleural mesothelioma (MPM), an aggressive and fatal cancer poorly responsive to current oncological treatments. Our aim was to: (a) compare EGFR immunohistochemical expression with mRNA levels measured by real time PCR; (b) assess the relationships between EGFR expression and clinico-pathological data including survival; (c) analyze the EGFR mutations. We developed an immunohistochemical method of EGFR evaluation based on the number of immunoreactive cells and staining intensity in 61 MPMs. EGFR immunoreactivity was documented in 34/61 (55.7%) cases. A significant correlation between EGFR protein and mRNA levels (p = 0.0077) was found, demonstrating the reliability of our quantification method of EGFR membrane expression. Radically resected patients (p = 0.005) and those with epithelial histotype (p = 0.048) showed an increased survival. No statistical correlation between EGFR immunoreactivity and patients survival was observed. No EGFR mutation was documented. This study documents EGFR overexpression in MPM at the protein and the transcriptional levels; it proposes a reliable method for EGFR expression evaluation in MPM. EGFR levels are not associated with clinico-pathological features of patients, including survival.

Unusual clear cell variant of epithelioid mesothelioma

Clear cell mesothelioma is an extremely rare neoplasm of the pleura, which can easily be mistaken for a metastasis of clear cell carcinoma to the pleura. We report here the histochemical, immunohistochemical, and ultrastructural aspects of a new case of clear cell pleural mesothelioma in a 52-year-old man with no known asbestos exposure. He was admitted to the hospital for recurrent pleural effusion, which was negative for neoplastic cells at the cytologic examination. A partial decortication of the right pleura was performed. The morphologic, immunohistochemical, and ultrastructural features reported for this case are consistent with the diagnosis of clear cell mesothelioma. The differential diagnosis and immunohistochemical features in comparison with other clear cell neoplasms are discussed.

Primary intrathoracic meningioma: histopathological, immunohistochemical and ultrastructural study of two cases

Meningiomas are common, usually benign slow-growing neoplasms of the central nervous system thought to arise from meningocytes capping arachnoid villi. Primary ectopic meningiomas are exceedingly rare extracranial and extraspinal tumors of controversial origin; they are usually limited to the head and neck region or to the paravertebral soft tissues. Only one mediastinal ectopic meningioma and few pulmonary ectopic meningiomas have been described in the literature until now. Because of their rarity and their intriguing pathogenesis, we report here a second case of primary mediastinal meningioma and an additional case of primary pulmonary meningioma. Their possible origin and differential diagnosis are discussed.

[Surfactant protein and thyroid transcription factor 1 in pleuro-pulmonary neoplasia. Immunohistochemical study]

Aim of this work was to investigate the ability of the antibodies against Surfactant proteins (SP) and Thyroid transcription factor 1 (TTF-1) to distinguish primary neoplasms of the lung from metastatic carcinomas to the lung and pleural mesotheliomas. We evaluated the immunohistochemical expression of the antibodies anti SP-A, SP-B, pro SP-C, SP-D, and TTF-1 in a series of 56 primary lung carcinomas, 9 metastatic carcinomas to the lung, 5 pleural mesotheliomas and 8 non-pulmonary carcinomas. Among primary lung neoplasms, only adenocarcinomas immunostained for all SP (specificity = 1; total sensitivity = 0.52). TTF-1 had an excellent specificity (= 1), but a weak sensitivity (= 0.34) in recognizing primary lung carcinomas. TTF-1 was present in lung adenocarcinomas which were negative for SPs; however it failed to distinguish the subtypes. Pleural mesotheliomas, pulmonary metastases and non-pulmonary carcinomas were not immunoreactive for SP-A, SP-B, SP-D, and TTF-1. Pro SP-C was positive also in the adenocarcinomas of the large bowel and in their pulmonary and nodal metastases. These results demonstrate that the combined use of antibodies anti SP-A, SP-B and TTF-1 is the best association in distinguishing primary lung carcinomas from metastatic carcinomas to the lung and pleural mesotheliomas.

Peripheral papillary tumor of type-II pneumocytes: a rare neoplasm of undetermined malignant potential

Peripheral papillary adenomas of the lung are uncommon neoplasms (only ten cases have been described so far in the English literature) composed predominantly of type-II pneumocytes and generally considered benign. We describe here two additional cases of this lung tumor. In both cases histological examination revealed an encapsulated papillary neoplasm with invasion of the capsule and, in one case, invasion of the adjacent alveoli and visceral pleura too. The proliferative index (Ki67) was less than 2% and the epithelial cells were positive for cytokeratins, surfactant apoproteins (SP), and nuclear thyroid transcription factor-1 (TTF- 1). Ultrastructurally, the epithelial cells showed the characteristic surface microvilli and cytoplasmic lamellar inclusions of type-II cells. Review of the literature has revealed two other cases of peripheral papillary adenoma of type-II pneumocytes with infiltrative features. Thus, we propose replacing the term peripheral papillary adenoma with peripheral papillary tumor of undetermined malignant potential.

Impact of the Pathfinder in a cytology laboratory

OBJECTIVE

To assess the value of Pathfinder (CompuCyte, Cambridge, Massachusetts, U.S.A.) in improving adequacy and accuracy of screening and supporting quality control programs.

STUDY DESIGN

The investigations were carried out on cervical cytologic smears only. Screening adequacy was assessed through the evaluation of percentage of slide coverage, percentage of overlapping and amount of elapsed time on smears screened with or without the Pathfinder by junior (426 cases) and senior (1,552 cases) screeners. Screening accuracy was investigated by comparing the performances of the same observer when reexamining, with the Pathfinder, a series of 1,051 cases already evaluated without the Pathfinder at least three months earlier. The review process was analyzed by both monitoring the elapsed time for relocation of manually or electronically marked cells (824 fields in 80 smears) and by comparing diagnostic discrepancies after the review of two series (74 + 74 cases) of randomly selected negative cases screened with or without Pathfinder.

RESULTS

Pathfinder-assisted screening increased the number of cases with optimal slide coverage (> or = 90% of screenable area) and optimal overlapping (between 15% and 20%) by both junior (P < .00001 and P < .00001) and senior (P < .00001 and P < .0003) screeners. It also improved screening accuracy by decreasing the number of cases "unsatisfactory for evaluation" (P < .00001) (as a consequence of better coverage and overlapping) and the number of diagnostic discrepancies detected after review (P = .05). During the latter process, the time elapsed for relocation of electronically marked fields, as compared to manually marked ones, was greatly reduced (1 hour, 25 minutes saved for revision of 40 smears).

CONCLUSION

In these preliminary studies, the Pathfinder was a useful tool for both education and diagnosis (screening and review) in a cytology laboratory.

Pancreatic malignant melanoma with occult primary lesion. A case report

A case of unusual location of a M.M. in the head of pancreas is described. Evidence of a primary lesion was not achieved, still we incline to retain this case as a metastatic malignant melanoma with occult primary location.

Duodenal gangliocytic paraganglioma. Report of a case and review of the literature

A case of gangliocytic paraganglioma (GP) of the ampulla of Vater is reported and the literature reviewed, with special attention to immunohistochemical studies. The present case, which occurred in a 56-year-old woman, shows the typical histological admixture of epithelioid, ganglion and spindle cells. Immunohistochemistry reveals strong reactivity for synaptophysin, Leu-7, somatostatin, S-100 protein and vimentin. A few ganglion cells are reactive for neurofilaments. Chromogranin A, myelin basic protein, desmin and cytokeratin are absent. Immunohistochemical data from literature regarding the cytoskeletal composition of GPs are not unequivocal: cytokeratin and neurofilament positivity is reported by some authors and denied by others. More uniformity is reported concerning the peptides produced by GPs: somatostatin and pancreatic polypeptide are the most frequently found antigens, followed by serotonin. General neuroendocrine markers like neuron specific enolase and protein gene product 9.5 are always positive, whereas chromogranins are rarely found. S-100 protein is always positive in the spindle cell component. Our data are in keeping with those previously reported and add the diffuse positivity for the Leu-7 antigen and the positivity of ganglion cells for synaptophysin. The nature of the tumour is still a matter of debate and it is difficult to agree with either of the proposed hypotheses--hamartoma/choristoma versus true neoplasm. However the recent reports of the occasional malignant evolution of GPs may support their true neoplastic nature.