Immunohistochemical profile of the pulmonary vasculature in subjects with cirrhosis and histopathologic evidence of pulmonary vascular disease: An autopsy study.

Portopulmonary hypertension (POPH) is a complication of cirrhosis that results in right ventricular failure and death. The objective of this autopsy investigation was to compare pulmonary arterial receptors in subjects with cirrhosis and histopathologic evidence of pulmonary vascular disease (PVD) and control group subjects with cirrhosis lacking evidence of PVD. Autopsy records of 824 subjects with cirrhosis were reviewed to identify pulmonary arterial vasculopathy. Lung sections from paraffin embedded blocks were immunostained for endothelin A (ET-A), endothelin B (ET- B), estrogen α (ER-α), estrogen ß (ER-ß), and vascular endothelial growth factor (VEGF). Subjects with cirrhosis and histopathologic evidence of PVD included 27 individuals with intimal hyperplasia (93%), medial hypertrophy (96%), and plexiform lesions (78%). Immunohistochemical staining for ET-A revealed positive reactivity in 40% of the group with cirrhosis and histopathologic evidence of PVD and 13% of the control group (NS). ET-B reactivity in the pulmonary endothelium and smooth muscle was identified in all subjects with cirrhosis and histopathologic evidence of PVD and control group. VEGF reactivity was identified in the endothelium in all subjects with cirrhosis and histopathologic evidence of PVD compared with 33% of the control group (p = 0.0002). ER-ß reactivity was observed in four subjects (26.6%) with cirrhosis and histopathologic evidence of PVD while none in the control group (NS). Cirrhosis and histopathologic evidence of PVD was found in 3.3% of autopsies with the pulmonary vasculature immunohistochemical profile demonstrating endothelial and smooth muscle reactivity for endothelin, VEGF and ER-ß.

Expression of glutathione S-transferase pi and glutathione synthase correlates with survival in early stage non-small cell carcinomas of the lung.

The glutathione S-transferase (GST) family of genes encode for detoxification enzymes that protect against reactive oxygen species and influence host susceptibility to carcinogens, including tobacco smoke. It has not been determined whether isoenzyme GST-pi or glutathione synthase (GSH2) expression by tumor cells bears a relationship to survival. A total of 201 non-small cell lung cancers (NSCLC) with long-term follow-up were immunostained with antibodies to GST-pi and GSH2 using standard immunostaining techniques. Results were graded semiquantitatively using a scale of 0 to 3 (0 < or = 10%; 1 = 10%-50%; 2 = 51%-80%; 3 > or = 80%) for both nuclear and cytoplasmic staining. Results were correlated with patient survival using Kaplan-Meier analysis. Nuclear staining with GST-pi in greater than 10% of the cells was closely associated with decreased survival (P = .02) in stage I and II squamous cell carcinomas (n = 40). Cytoplasmic staining showed a similar trend that did not reach statistical significance. No significant correlation between GST-pi staining and survival was determined for other histologic types of NSCLC. Cytoplasmic GSH2 staining in greater than 80% of tumor cells was associated with a trend toward improved survival for stage I adenocarcinoma (P = .08) but did not show a relationship to survival for other histologic types of NSCLC. GST-pi expression predicts prognosis in stage I and II squamous cell lung carcinoma, and GSH2 expression may indicate better survival in early stage adenocarcinoma of the lung. Manipulation of GST-pi and GSH2 may be a potential basis for treatment of some NSCLC.

Activation of the hedgehog pathway in a subset of lung cancers.

Activation of the hedgehog pathway is reported in lung cancer, but its frequency remains unknown. We examine activation of this pathway in lung cancers by in situ hybridization and immunohistochemstry, and find that less than 10% of the tumors have elevated hedgehog target gene expression. We further identify a cell line NCI-H209 and two primary tumors with no detectable Su(Fu), a negative regulator of the pathway. Ectopic expression of Su(Fu) in NCI-H209 cells down-regulates hedgehog target gene expression and leads to inhibition of cell proliferation. These data indicate that activation of the hedgehog pathway is activated through Shh over-expression or Su(Fu) inactivation in only a subset of lung cancers.

The incidence of rotator cuff disease in smoking and non-smoking patients: a cadaveric study.

The etiology of rotator cuff disease is multifactorial. One theory behind the high incidence of rotator cuff tears in the shoulder is that the supraspinatus/infraspinatus tendon contains a zone of relative avascularity in the area proximal to its insertion at the greater tuberosity. Tobacco smoking is known to contribute to microvascular disease, and it can be hypothesized that smoking tobacco further compromises the vascular supply to the supraspinatus/infraspinatus tendon, thus increasing the incidence of tendinous pathology in the rotator cuff. This article evaluates the rotator cuffs of 72 shoulders in 36 cadavers and compares the incidence of macroscopic and microscopic disease within the rotator cuff tendon. Microscopic evaluation of the accompanying lung tissue from the respective cadaver also was performed. As a result, we were able to determine the presence or absence of a smoking history or emphysema from each cadaver as it related to rotator cuff disease in the shoulder. Of the 36 shoulders that exhibited macroscopic rotator cuff tears, 23 were from cadavers with a history of smoking compared to only 13 from cadavers with no history of smoking. Furthermore, the presence of advanced microscopic rotator cuff pathology (Grade 3 or 4 fibrous degeneration) was more than twice as likely in the cadavers with a history of smoking (22/32) compared to only 10 of 32 shoulders from cadavers with no history of smoking. While none of this data was statistically significant due to the insufficient number of subject cadavers, strong trends were noted in these findings.

Impact of Recent Developments in Lung Cancer on the Practice of Pathology.

Landmark events in the field of lung cancer in the past year have the potential to significantly alter the practice of pathology. Three key events are (1) approval of payment for low-dose computed tomography screening for lung cancer, (2) publication of an extensively revised World Health Organization classification of lung cancers, and (3) approval of immunohistochemistry based companion diagnostics by the US Food and Drug Administration. We briefly review these milestones in the context of their impact on the practice of pathology.

Folate Receptor α Expression Level Correlates With Histologic Grade in Lung Adenocarcinoma.

CONTEXT: -Folate receptor α (FRA) is a glycosylphosphatidylinositol-anchored high-affinity folate receptor that localizes to the apical surface of epithelia when it is expressed in normal tissue. Unlike normal tissues, FRA may localize to the basolateral side in tumors. These features make FRA an attractive drug target, and several FRA-targeted drugs have been developed and are in phases of clinical testing. Folate receptor α protein expression shows intertumoral variability that may correlate with response to therapy and to clinicopathologic parameters. Using immunohistochemistry, a recent study of breast carcinomas found FRA protein expression was associated with triple-negative status and high histologic grade in breast cancer. Although a prior study of lung adenocarcinomas found the expression level of the gene encoding FRA, FOLR1, was significantly increased in low-histologic-grade tumors compared to high-histologic-grade tumors, the relationship between FRA protein expression and histologic grade has not been reported for lung adenocarcinomas. OBJECTIVE: -To investigate the relationship between FRA protein expression level and clinicopathologic parameters in lung adenocarcinomas, including histologic grade, by performing immunohistochemistry for FRA on a cohort of non-small cell lung carcinomas. DESIGN: -High-density tissue microarrays constructed from 188 non-small cell lung carcinomas and used in prior studies were immunostained with FRA-specific antibody clone 26B3. Folate receptor α membranous staining intensity was given a semiquantitative score from 0 to 3+ for triplicate cores of tumor and averaged for each tumor. An average semiquantitative score from 0 to 1.4 was considered low expression, and an average semiquantitative score greater than 1.4 was considered high expression. RESULTS: -The majority (60 of 78; 77%) of lung adenocarcinomas and a minority (4 of 41; 10%) of lung squamous cell carcinomas were positive for FRA. Folate receptor α expression in lung adenocarcinomas compared with squamous cell carcinomas was statistically different (P < .001, χ(2) test). In lung adenocarcinomas, FRA expression level correlated with histologic grade (P = .005, χ(2) test for trend), but no other clinicopathologic parameter. The majority (23 of 27; 85%) of grade 1 adenocarcinomas had high FRA protein expression, whereas approximately half of grade 2 (10 of 19; 53%) and grade 3 (12 of 25; 48%) adenocarcinomas had high FRA protein expression. Out of adenocarcinomas with lepidic growth pattern, 16 of 20 (80%) showed high FRA protein expression. Out of adenocarcinomas with solid growth pattern, 2 of 6 (33%) showed high FRA protein expression. In lung adenocarcinomas, FRA expression level did not correlate with thyroid transcription factor 1, napsin A, or survival. CONCLUSIONS: -Folate receptor α protein was expressed in the majority of lung adenocarcinomas and a minority of lung squamous cell carcinomas. Folate receptor α protein expression correlated with histologic grade for lung adenocarcinomas, and the greatest difference was observed between grade 1 and grade 3. Our results indicate that poorly differentiated adenocarcinomas or focuses of poor differentiation in a heterogeneous tumor may lack FRA protein expression and be more likely to be resistant to FRA-targeting drugs.

Pulmonary hypertension in sickle cell hemoglobinopathy: a clinicopathologic study of 20 cases.

Pulmonary hypertension is one of the major causes of morbidity and mortality of patients with sickle cell hemoglobinopathy (SCH). Although a clinically recognized complication of sickle cell disease (SCD), there are few published pathologic studies of pulmonary findings in these patients. The aim of this study was to define the pulmonary pathologic changes and to investigate correlation between the pathologic changes, the antemortem diagnosis of pulmonary hypertension, and the severity of SCH. Cases of SCH were identified from the autopsy database using Snomed codes. Clinical and echocardiograph data were collected for correlation with the pathologic data. A total of 20 adult patients (12 males and 8 females) were identified. Hemoglobin electrophoresis results were available for 16 patients, with hemoglobin S fraction percentages ranging from 23% to 97.8%. Eleven patients had SCD, 5 patients had sickle cell trait (SCT), and the remaining 4 patients without hemoglobin electrophoresis were included in the SCT group. The mean age of the SCT group was higher than that of the SCD group (P = 0.03). Histologically, all 20 patients demonstrated changes in pulmonary vasculature considered diagnostic of pulmonary hypertension grade I to grade IV, associated with plexiform lesions in 60% of patients. Medial hypertrophy and intimal hyperplasia/fibrosis, considered potentially reversible lesions, were seen in all patients. A weak association was found between SCD and plexiform lesions. Fibroelastic degeneration of small arteries, arterioles, and venules was identified in almost all (95%) cases. Clinically, tricuspid regurgitation was detected by echocardiogram in 10 of 20 (50%) patients; 6 of these 10 had significant regurgitation to allow estimation of systolic pressure. Sudden death occurred in 8 patients, with males having a significantly higher incidence. Cardiomegaly was present in 95% of patients, however, autosplenectomy and hepatic cirrhosis/hemochromatosis were observed almost exclusively in patients with SCD. Cirrhosis was found to have a strong positive association with SCD. This study demonstrates pulmonary hypertensive changes in all 20 autopsied patients who had SCH but died from various causes. We conclude that a high prevalence of pulmonary hypertension is associated with SCH with consequent high mortality. Therefore, patients with SCH would benefit from a regular periodic assessment for pulmonary hypertension regardless of age, sex, and severity of hemoglobinopathy.

Immunohistochemical study of thyroid transcription factor-1 and HER2/neu in non-small cell lung cancer: strong thyroid transcription factor-1 expression predicts better survival.

The relationship of thyroid transcription factor-1 (TTF-1) and HER2/neu expression in non-small cell lung cancer (NSCLC) with multiple parameters including survival were examined. Patients with primary NSCLC who had surgical resection and follow-up of at least 5 years were included in the study. There were 57 patients (38 men and 19 women), 44 to 75 years old (median age, 61 years); 28 patients had adenocarcinoma (AD) and 29 had squamous cell carcinoma. Tumors were examined for TTF-1 and HER2/neu expression using formalin-fixed, paraffin-embedded tissue. Clinical and follow-up data were obtained from the hospital records and Cancer Center database. Representative tumor sections were stained using standard immunohistochemical technique and commercial antibodies for TTF-1 (clone 8G7G3/1, Dako) and HER2/neu (polyclonal, Dako). Tumors were graded as negative (<5%), weak positive (5-49%), and strong positive (>50%), based on the percentage of positively stained tumor cells. Statistical analyses were performed using log-rank test, Pearson and Spearman correlations, and Kaplan-Meier survival curves. TTF-1 expression was seen in 45.6% of all tumors (80% of ADs and 14% of squamous cell carcinomas). Eighteen patients with tumors showing strong TTF-1 expression had significantly better survival compared with the 39 patients whose tumors showed negative or weak TTF-1 expression, although many more of the higher stage AD had strong TTF-1 staining than stage I AD. The TTF-1 expression did not correlate with tumor differentiation and was considered an independent predictor of survival. Seventeen of the 18 tumors with strong TTF-1 expression were ADs. Only eight of 57 (17%) tumors showed HER2/neu expression; seven of these eight were ADs. Although HER2/neu expression and survival did not show correlation, the majority of those ADs with weak or strong HER2/neu staining also had strong TTF-1 staining, were mostly stage I tumors. and had overall longer survival. All patients with stage I disease showed better 5-year survival compared with those with stages II and III. Hispanic patients had significantly worse survival compared with Caucasians and African Americans. The results of this study suggest that strong expression of TTF-1 is an independent predictor of better survival and may be a useful prognostic tool for evaluation of patients with NSCLC.

CYP2E1 polymorphism, cigarette smoking, p53 expression, and survival in non-small cell lung cancer: a long term follow-up study.

The expression of selected gene products involved in cell differentiation and cell growth and genetic polymorphism of detoxifying genes was examined in 105 surgically resected nonsmall cell lung cancer (NSCLC) patients, and the relationship of these factors was correlated with cigarette smoking and patient survival. Genotyping of peripheral blood lymphocytes from 87 patients was performed for CYP2E1, GSTM1, GSTT1, mEH, and MPO detoxifying genes using polymerase chain reaction. Formalin-fixed, paraffin-embedded tissue was immunostained with antibodies to p53, p27, phospho-AKT, and bcl-2 using the avidin-biotin-peroxidase method and tissue microarray technique. Tumors were assigned a positive or negative score based on more than 10% of tumor cells staining positive with the antibody. The subtypes of NSCLC included 48 adenocarcinomas, 47 squamous cell carcinomas, and 10 large cell undifferentiated carcinomas. A total of 54 tumors were pathologic stage I, 23 were stage II, and 26 were stage III. All subjects smoked (range, 10-175 pack-years; mean, 60 pack-years). The mean overall survival was 112 weeks (median, 129 weeks). Patients with p53-positive tumors had significantly fewer pack-years of smoking (52 pack-years vs 72 pack-years; P = 0.021), smoked fewer years (34 years vs 40 years; P = 0.018), and had significantly better survival compared with those with p53-negative tumors (P = 0.045). When smoking history was further analyzed, the authors found that p53 expression was associated with the number of years smoked and not the number of packs smoked per day. Patients with squamous cell carcinoma had smoked longer compared with those with adenocarcinoma (P = 0.011). Significant association was seen between the CYP2E1 wild-type allele and better survival (P = 0.016). Patients with stage I tumors had better survival compared with stages II and III (P = 0.032). No association was found between survival and tumor type; tumor differentiation; expression of phospho-AKT, p27, and bcl-2; and polymorphic metabolizing genes other than CYP2E1. The significant association of long duration of smoking (>40 years) with loss of p53 expression and poor survival suggests inactivation of the protective p53 pathway in those who had a history of more than 40 years of smoking.

Desmoplastic small round cell tumor of the lung.

An extra-abdominal desmoplastic small round cell tumor (DSRCT) of the lung with immunohistochemical, ultrastructural, and cytogenetic evidence of multidirectional differentiation is reported. We demonstrate that DSRCTs of the lung and pleura show morphologic, molecular, genetic, and ultrastructural features similar to DSRCTs arising in other sites. The tumor showed coexpression of cytokeratins (AE1/3, epithelial membrane antigen, CAM 5.2) and mesenchymal markers (vimentin, desmin, neuron-specific enolase), as well as WT1. Ultrastructurally, intracytoplasmic whorls of intermediate filaments, similar to previous descriptions of DSRCT in nonthoracic sites, were also demonstrated in this case. EWS-WT1 gene fusion characteristic of DSRCT with the t(11;22)(q13;q12) translocation was demonstrated in this tumor.

Hibernoma: a report of 2 unusual cases with a review of the literature.

Hibernomas are rare neoplasms composed of brown adipose tissue. The behavior of these neoplasms has been described as uniformly benign in humans. The only recurrence cited in the English literature involved a sarcoma with hibernoma-like features, which was reported in abstract form. We present 2 cases of hibernoma, one that continued to grow following partial excision and another at an unusual site (anterior abdominal wall). Both of these tumors overexpressed p53 protein by immunohistochemistry, which was a novel finding. A review of the literature highlights recent advances that may help confirm the diagnosis and explain the biology of these rare tumors.

Ocular pathology in acquired immunodeficiency syndrome.

Gross and microscopic ocular findings were prospectively studied in 38 human immunodeficiency virus (HIV)-seropositive subjects undergoing postmortem examination. Pathologic lesions were detected in 27 patients (71%), with 67% of the abnormal findings detected only microscopically.

Double lung transplantation for diffuse idiopathic pulmonary neuroendocrine cell hyperplasia.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare cause of obstructive lung disease and a proposed precursor of pulmonary carcinoid tumors. With increased awareness of this disease, an accumulating number of cases have been reported. Patients may have progressive shortness of breath due to small airway obstruction. There is limited information on treatment of the disease, particularly for those with progressive disease. Here we report 2 patients who were treated at our institution with double lung transplantation. Both patients were female nonsmokers with a clinical presentation of cough and dyspnea. Multiple bilateral lung nodules were identified on high-resolution computed tomography and pulmonary function tests showed obstructive pattern in both patients. The diagnoses of DIPNECH were made by histologic evaluation of the explanted native lungs. These 2 patients are in stable condition following double lung transplantation at the time of this report. DIPNECH is increasingly recognized due to improved sensitivity of investigative imaging and increased awareness of the entity. Considering the malignant potential and lack of effective treatment of the disease, lung transplantation could be potentially an effective treatment option for these patients.

The presence of anti-HLA donor-specific antibodies in lung allograft recipients does not correlate with C4d immunofluorescence in transbronchial biopsy specimens.

CONTEXT: C4d immunofluorescence (IF) is a surrogate for development of donor-specific antibodies (DSAs) against human leukocyte antigen (HLA) class I and II antigens in kidney and heart biopsy specimens for monitoring of antibody-mediated (humoral) allograft rejection (AMR). Use of C4d IF in monitoring of lung allografts has shown conflicting results. OBJECTIVE: To determine if C4d IF can be used as a reliable marker for AMR and if it correlates with the presence of DSAs and histologic findings on biopsy. DESIGN: All transbronchial biopsies in lung allograft recipients, performed at our institution in a 3-year period, were reviewed. A cohort of 92 patients with 110 corresponding biopsies met the inclusion criteria of (1) having a resulted DSA within 2 weeks of biopsy and (2) having C4d immunofluorescence studies performed and confirmed. RESULTS: Twenty-nine patients (31.5%) were positive for DSAs and 63 patients (68.5%) did not develop DSAs. Positive C4d capillary IF was seen in 18 of 110 total biopsy specimens (16.4%). Eight of these biopsy samples were from patients positive for DSAs and 10 were from patients negative for DSAs. The correlation coefficient between the presence of DSAs and C4d IF was 0.1628 (P = .09). CONCLUSIONS: A significant proportion of DSA-positive patients had negative C4d IF results and frequently have no histologic changes on biopsy specimens. DSA-negative patients can be positive for C4d and may show the same histologic changes as reported for DSA-positive patients. Diagnosis of AMR in lung may require a collaborative approach combining clinical data, DSA status, and histology.

Application of immunohistochemistry to infections.

CONTEXT: Pathologists play an important role in the diagnosis or exclusion of infectious diseases. Traditionally, the diagnosis of infectious diseases rely on serologic assays and cultures. Serologic results may be difficult to interpret in the setting of immunosuppression, fresh tissue is not always available for culture, and culture of fastidious pathogens can be difficult and may take weeks or months to yield a result. Although some microorganisms or their cytopathic effects may be readily identifiable on routine and/or histochemical stains, often these changes are not specific or are sparse in the sample evaluated. In these cases, additional immunohistochemical stains are often needed to establish the diagnosis of infection. OBJECTIVE: To review the current value and limitations of the use of immunohistochemistry in the diagnosis of infectious diseases in formalin-fixed tissue samples. DATA SOURCES: Literature in Medline and the authors' own experience. CONCLUSIONS: Immunohistochemistry has proven to be a useful tool in the diagnosis of infectious diseases in tissue samples. Immunohistochemistry is especially useful in the identification of microorganisms that are present in low numbers, stain poorly, are fastidious to grow, are noncultivable, or exhibit an atypical morphology. Finally, it is important to remember that there may be widespread occurrence of common antigens among bacteria and pathogenic fungi and both monoclonal and polyclonal antibodies must be tested for possible cross-reactivity with other organisms.

Pulmonary and cardiovascular complications of obesity: an autopsy study of 76 obese subjects.

CONTEXT: Obesity is associated with sleep disordered breathing and cardiovascular morbidity, but the relationship between pulmonary hypertension, heart disease, and obesity is unknown. OBJECTIVE: To determine the prevalence of pulmonary and cardiovascular disease in obese subjects undergoing autopsy at a large medical center. DESIGN: A search through autopsy records from an 11-year period identified 76 subjects with a body mass index greater than 30 kg/m(2) and 46 age-matched, nonobese controls. Clinical data were collected from medical charts and autopsy records. Formalin-fixed, paraffin-embedded sections of lungs and heart were reviewed for each subject. The presence of pulmonary edema, hemorrhage, diffuse alveolar damage, thrombi, and pulmonary hypertensive changes, including intimal fibrosis, medial hypertrophy, muscularization of arterioles, alveolar capillary hemangiomatosis, hemosiderosis, and iron encrustation were documented. Hearts were examined for the presence of cardiomegaly, ventricular hypertrophy, coronary artery atherosclerosis, acute infarction, fibrosis, and inflammation. Differences between the obese and control groups were compared using a statistical software program. RESULTS: The obese group demonstrated a greater occurrence of diabetes mellitus, systemic hypertension, pulmonary edema, hemorrhage, and pulmonary hypertensive changes compared with the control group. Alveolar capillary hemangiomatosis was exclusively observed in the obese subjects. Cardiomegaly and left ventricular hypertrophy were present in all obese subjects; approximately one third of the obese subjects had no coronary atherosclerosis. CONCLUSIONS: Pulmonary hypertensive changes, including venous hypertension and capillary hemangiomatosis, were observed in 72% of obese subjects. Cardiomegaly with biventricular hypertrophy was present in all obese subjects and was suggestive of obesity cardiomyopathy.

MUC4 expression in non-small cell lung carcinomas: relationship to tumor histology and patient survival.

CONTEXT: Mucin 4 (MUC4) is a high-molecular-weight membrane-bound glycoprotein that is expressed in the foregut before epithelial differentiation. It is found in normal adult airway epithelium, non-small cell lung carcinoma (NSCLC) and in other human malignancies independent of mucus secretion. Although its tissue distribution has been studied, its utility in predicting prognosis in NSCLC is unknown. OBJECTIVE: To evaluate the relationship between MUC4 overexpression and long-term survival in patients with NSCLC. DESIGN: Immunohistochemical staining for MUC4 was performed on formalin-fixed, paraffin-embedded tissue samples from 343 cases of NSCLC arranged in a high-density tissue microarray. Information about long-term survival and tumor stage was collected for all patients. Semiquantitative assessment of MUC4 staining was correlated with survival (Kaplan-Meier analysis). RESULTS: MUC4 was frequently expressed in adenocarcinomas (151/187 [81%]), squamous cell carcinomas (69/ 88 [78%]), adenosquamous carcinomas (6/8 [75%]), and large cell carcinomas (33/60 [55%]). High levels of expression (combined score, 2+/3+) for MUC4 were more characteristic of adenocarcinomas (126/187 [68%]) and adenosquamous carcinomas (6/8 [75%]) than of squamous cell carcinomas (46/88 [52%]) and large cell carcinomas (17/60 [28%]) (P < .001). In patients with stage I and II adenocarcinoma, there was a trend toward longer patient survival with higher levels of MUC4 immunoreactivity compared with lower levels (P = .11). CONCLUSION: MUC4 expression is common in pulmonary adenocarcinomas and may indicate a more favorable prognosis in early-stage adenocarcinomas.

Expression of renal cell carcinoma-associated markers erythropoietin, CD10, and renal cell carcinoma marker in diffuse malignant mesothelioma and metastatic renal cell carcinoma.

CONTEXT: Metastatic renal cell carcinoma (MRCC) involving the thorax can be difficult to distinguish from diffuse malignant mesothelioma (DMM) using traditional morphologic approaches. Standard panels of immunohistochemical markers are of limited benefit. OBJECTIVE: To investigate several antibodies to renal cell carcinoma-associated proteins for differentiating MRCC from DMM. DESIGN: One hundred DMMs and 20 MRCCs were evaluated for immunoexpression of erythropoietin. The same cases and an additional 45 DMMs were evaluated for CD10 and renal cell carcinoma marker (RCCMa) immunoreactivity. RESULTS: Erythropoietin was expressed in 100% of DMMs and MRCCs. Staining for CD10 was observed in 54% of DMMs and 100% of MRCCs. RCCMa stained 26% of DMMs and 55% of MRCCs. Although erythropoietin staining was similarly strong and diffuse in both DMM and MRC, patterns of staining for RCCMa and CD10 differed between MRCC and DMM. Immunoreactivity was strong and diffuse for both RCCMa and CD10 in most MRCCs. Of CD10-positive DMMs, nearly half showed staining in less than 50% of tumor cells and about one fourth of positive cases exhibited only weak to moderately intense staining. Only half of RCCMa-positive DMMs showed staining in more than 49% of tumor cells and staining was only weak to moderately intense in most cases. CONCLUSIONS: Given the overlap in the expression of renal cell carcinoma markers in MRCC and DMM, results with these markers must be interpreted cautiously and should be used in conjunction with mesothelium-associated markers. Differences in expression may potentially help distinguish MRCC from DMM inasmuch as strong and diffuse expression of RCCMa and CD10 supports a diagnosis of MRCC over DMM.

Small cell carcinoma of the ovary with hypercalcemia and ectopic parathyroid hormone production.

Small cell carcinoma of the ovary is a rare malignant tumor of the ovary. It is the most common undifferentiated ovarian carcinoma in young women. Approximately two thirds of patients with ovarian small cell carcinoma have hypercalcemia. The mechanism of development of hypercalcemia is unclear, although parathyroid hormone-related protein has been found in some of the cases. Parathormone expression in tumor cells, rarely reported, was seen in this case, suggesting that ectopic parathyroid hormone production by the tumor cells may be the cause of hypercalcemia.