Synchronous diffuse malignant mesothelioma and carcinomas in asbestos-exposed individuals

Colorectal Cancer and Asbestos Exposure: A Women's Health Perspective

BACKGROUND

Colorectal cancer (CRC) is considered a "man's disease". However, emerging data show that females may have a higher prevalence of certain risk factors. A potential causal role of asbestos in CRC carcinogenesis has been suggested. This relationship is controversial, and only a few studies have focused on exposed female populations. The aim of this study was to review the scientific literature related to asbestos-related CRC incidence and mortality rates in female populations to address gender bias in the existing research.

METHODS

A systematic review was performed following PRISMA statement.

RESULTS

Fourteen studies reporting 92 cases in total were included. Most women were aged 50 years or older and were employed in occupational activities with high asbestos exposure (steel, textile, and asbestos-cement industry) for at least 10 years. In one single case, household asbestos exposure was reported. The colon was the primary location of the tumor in 47 out of 92 cases. Three women were also affected by synchronous or metachronous peritoneal mesotheliomas.

CONCLUSIONS

This study revealed a general methodological "gender bias" in scientific research. A significantly higher representation of women in clinical studies is needed to clarify the link between asbestos exposure and the development of colorectal cancer.

Successful treatment of simultaneous malignant pleural mesothelioma and pulmonary adenocarcinoma: A case report

The present report described the case of a 74-year-old male patient with asbestos exposure whose chest computed tomography revealed a right lower lobe nodule and right pleural effusion. Pleural biopsy led to the diagnosis of epithelial malignant pleural mesothelioma (cT2N0M0, stage IB). Combination therapy with cisplatin + pemetrexed led to the complete remission of malignant pleural mesothelioma; however, the right lower lobe nodule grew in size over time. The patient was subsequently diagnosed with lung adenocarcinoma (cT1aN0M0, stage IA1) by computed tomography-guided biopsy performed 18 months after chemotherapy initiation and achieved remission of lung adenocarcinoma with stereotactic radiotherapy. The patient was alive without recurrence at the 12-month follow-up. The present case illustrated that multiple active regimens are currently available for malignant pleural mesothelioma and lung cancer that can aid in the treatment of complex cases.

Second Primary Cancers in a Population-Based Mesothelioma Registry

Background: The presence of a second primary cancer (SPC) in patients with pleural mesothelioma (PM) may impact overall survival and suggest a common mechanism of carcinogenesis or an underlying germline genetic alteration. Methods: We evaluated the occurrence of SPCs within PM cases collected from 2000 to 2018 by the Lombardy Mesothelioma Registry and their prognostic implications. Kaplan–Meier analysis was performed to estimate median survival times, together with univariate and multivariate Cox regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) of death. Results: The median overall survival (OS) of the entire study population (N = 6646) was 10.9 months (95% CI: 10.4–11.2); patient age and histotype were the strongest prognostic factors. No substantial survival difference was observed by the presence of an SPC (10.5 months in 1000 patients with an SPC vs. 10.9 months in 5646 patients in the non-SPC group, HR 1.03, p = 0.40). Shorter OS in the SPC group was only observed in 150 patients with the non-epithelioid subtype (median OS of 5.4 vs. 7.1 months, HR 1.21, p = 0.03). Conclusions: The diagnosis of an SPC did not influence the outcome of PM patients in the overall study population but was associated with shorter OS in non-epithelioid cases. Further studies are needed to clarify the role of SPCs as markers of genetic susceptibility in mesothelioma.

Synchronous Malignant Peritoneal Mesothelioma and Sigmoid Adenocarcinoma: a Challenging Clinical Entity

Background

Malignant peritoneal mesothelioma (MPM) represents a rare clinical entity. The synchronous existence of MPM with other malignancies as colonic adenocarcinoma have been rarely reported. Its diagnosis and management are challenging given its complexity and rarity.

Objective

Herein, we report a case of epithelioid subtype of MPM occurring synchronously with sigmoid colonic adenocarcinoma, along with review of the literature.

Case presentation

An elderly female patient was referred as case of rectosigmoid mass. She reported history of abdominal pain, per-rectal bleeding, anorexia, and significant weight loss. Her computed-tomography scan of the abdomen revealed a fistulizing sigmoid mass and multiple enlarged lymphnodes with omental nodulation. The colonoscopy revealed a large fungating mass and the endoscopic biopsies were reported as colonic adenocarcinoma. The patient was scheduled laparoscopic low anterior resection. However, the diagnostic laparoscopy revealed several nodules disseminated all over the peritoneum, suggestive of peritoneal mesothelioma. Therefore, the decision was changed to create transverse colostomy after examination obtaining multiple biopsies from the omental and peritoneal nodules. The histopathological revealed MPM and the final diagnosis was sigmoid adenocarcinoma with synchronous MPM. The patient was started on palliative chemotherapy (capecitabine) without active management of MPM because of her general condition. She was followed up with a good clinical course.

Conclusion

MPM is an overlooked entity with vague clinical presentation. Synchronous MPM with colorectal cancer is rare with only few published case reports. Its diagnosis is challenging, and its management should be tailored according to the patient. This case is the first reported case in Saudi Arabia and the Middle East.

Malignant mesothelioma without asbestos exposure diagnosed during EGFR-TKI treatment of lung adenocarcinoma: A case report

Synchronous malignant mesothelioma (MM) and lung carcinoma are extremely rare in patients without a history of asbestos exposure and poses tremendous difficulties in clinical management. We report a patient without asbestos exposure diagnosed with MM during EGFR-TKI treatment of lung adenocarcinoma (LUAD), who responded to first-line chemotherapy with pemetrexed plus carboplatin and failed to subsequent systemic therapy. Clinicians should be careful about the possibility of MM comorbidity in LUAD patients whose lesions respond differently to EGFR-TKI, even in those without a history of asbestos exposure.

The forensic significance of pseudomesotheliomatous adenocarcinoma of the lung

Pseudomesotheliomatous carcinomas (PMC) are rare tumors that clinically, macroscopically, and sometimes histologically resemble malignant pleural mesotheliomas. We report a case of a 91 year woman who was found to have diffuse nodular pleural thickening and a lung mass during a workup for persistent cough. She declined rapidly and died before a histologic diagnosis could be made. Postmortem examination revealed a tumor that diffusely involved the pleural surface with local extension into the chest wall, pericardium, and diaphragm along with a concurrent lung mass. Histologic examination showed poorly-differentiated cells predominantly arranged in sheets, cords, and nests with focal glandular differentiation. An immunohistochemical panel of calretinin, WT1, BEREP4, MOC31, and TTF1 confirmed the diagnosis of primary lung adenocarcinoma. The macroscopic, histologic, and immunohistochemical features used to distinguish metastatic and primary lung adenocarcinoma from epithelioid malignant mesothelioma are discussed. The distinction of malignant mesothelioma from pseudomesotheliomatous carcinoma is important for medicolegal reasons regarding asbestos related compensation claims.

Synchronous presentation of muscle-invasive urothelial carcinoma of bladder and peritoneal malign mesothelioma

Introduction

Cancer is one of the most important leading cause of death in man and woman in the world. The occurrence of new cancer has become more frequent in recent years due to strict screening protocols and occupational and environmental exposure to carcinogens. The incidence of secondary malignancies has also increased due to close medical follow-up and advanced age. Herein, we report a case and its management diagnosed as synchronous peritoneal malignant mesothelioma and muscle-invasive urothelial carcinoma.

Case Description

A 71-year-old male presented with macroscopic hematuria and abdominal distension increasing gradually. A contrast enhanced computerized tomography demonstrated bladder mass and diffuse ascites with nodular peritoneal thickening and umbilical mass. He was treated with the multidisciplinary team working including urologist, medical oncologist and general surgeon.

Conclusions

To our knowledge, this is the first case of peritoneal malign mesothelioma with synchronous muscle-invasive urothelial carcinoma. Because of the rarity of this condition, there is still no consensus on the definitive treatment protocols, yet. Individualized treatment with multidisciplinary close follow-up might improve the survival outcomes.

Simultaneous presence of lung adenocarcinoma and malignant pleural mesothelioma: A case report

The co-presence of malignant pleural mesothelioma (MPM) and lung cancer is rare. We report a 70-year-old male with exposure to asbestos. Chest computed tomography revealed a right mediastinal mass combined with an enlarged ipsilateral lymph node and left pleural effusion. Transbronchial lung biopsy revealed lung adenocarcinoma. Thoracoscopic examination revealed multiple left pleural nodules, leading to the diagnosis of MPM. Despite aggressive anticancer drug therapy, he expired due to disease progression 2.5 years after diagnosis. Autopsy confirmed an epithelioid MPM in the left pleura. MPM comorbidity in patients diagnosed with lung cancer should be considered, especially in those exposed to asbestos.

Malignant Mesothelioma of the Pleuraand Other Malignancies in the Same Patient

Aims and background

The co-existence of mesothelioma, mostly asbestos-related, and other primary malignancies has repeatedly been reported. The present study evaluated the frequency of such an occurrence.

Methods

In the period October 1979-June 2002, 215 cases of malignant pleural mesothelioma were diagnosed at the Hospital of Monfalcone, Italy. All the cases of the above series, examined at necropsy (169), were included in the study. Occupational histories had been obtained from the patients or from their relatives by personal or telephone interviews. In 132 cases, asbestos bodies were isolated after chemical digestion of lung samples. The thoracic cavities were examined for pleural plaques.

Results

Additional malignancies were observed in 32 cases (18.9%). Multiple tumors were synchronous in 22 cases, metachronous in 8 cases, and synchronous and metachronous in 2. Four different tumors were found in 2 cases, 3 malignancies were detected in 6 patients, and 2 malignancies in the remaining 24. The most frequent additional malignancies were prostate adenocarcinoma (7 cases), non-Hodgkin lymphoma or chronic lymphocytic leukaemia (5 cases), bladder carcinoma (4 cases), kidney carcinoma (4 cases), large bowel carcinoma (4 cases), and liver cell carcinoma (4 cases). All the patients had histories of exposure to asbestos, mostly in shipbuilding. Lung asbestos body burdens ranged between 60 and 230,000 per gram of dried tissue. Pleural plaques were found in 26 cases.

Conclusions

In contrast with other series of the literature, in the present cases the co-existence of mesothelioma and other malignancies appeared as a relatively frequent event. The lack of a control group does not allow definite conclusions about the meaning of the occurrence. However, the co-existence of certain tumors with asbestos-related mesothelioma suggests that mesothelioma and associated malignancies might share some etiologic factors (asbestos and others).

Synchronous and Metachronous Malignant Epithelial and Lymphoid Tumors: a Clinicopathologic Study of 10 Patients from a Major Tertiary Care Center in Pakistan

Case reports and case series documenting unfortunate patients with more than one malignant neoplasm are rare but well established. While majority of such patients have two malignancies, cases with three or even four malignant neoplasms in the same patient have been published in literature. A number of factors influencing carcinogenesis have been implicated in such cases including exposure to large amounts of radiation, chemotherapy for the original malignancy; prolonged history of heavy smoking and exposure to other environmental carcinogens; aging; and underlying genetic alterations. Concomitant multiple malignant neoplasms may be synchronous-two or more malignant neoplasms histologically distinct from each other, arising in the same site and detected simultaneously (for example during the same hospital admission) or detected one after the other in sequence in a period less than 6 months; or metachronous-two or more malignant neoplasms of similar or distinct histologic type detected at different times (after an interval of greater than 6 months) in different anatomic sites. Any combination of malignant tumors can occur in the same patient for example carcinomas with other carcinomas, carcinomas with Non-Hodgkin or Hodgkin lymphomas, carcinomas with mesotheliomas, carcinomas with sarcomas etc. We have reported several cases with multiple malignancies during our practice, and these cases were composed of the different combinations described above. The aim of the present study is to document 10 such cases of combined carcinoma and Non Hodgkin lymphoma in the same patient which were diagnosed in our section.

Small bowel metastasis from pancreatic cancer in a long-term survival patient with synchronous advanced malignant pleural mesothelioma: A case report and literature review

Diffuse malignant pleural mesothelioma (MPM) is an aggressive tumor that originates from the surface of the pleura. Approximately 70% of cases are associated with chronic asbestos exposure. MPM is regarded as an incurable disease, with a median survival of ~2 years following intensive multimodality treatment. Pancreatic cancer is a malignancy also associated with a poor prognosis, with only 2% of patients surviving for 5 years. The majority of patients with pancreatic cancer are diagnosed with an advanced stage of disease and experience a poor response to therapy. The development of synchronous MPM and other types of cancer is rare. The present study describes a patient with synchronous, biphasic MPM and pancreatic adenocarcinoma, who was treated with a multimodal therapeutic approach with stereotactic body radiation therapy. Due to a suspected diagnosis of ‘acute abdomen’, an emergency small intestine resection was performed and a subsequent diagnosis of moderately-differentiated adenocarcinoma was confirmed. During a further immunohistochemical examination, pathologists determined that the small bowel metastasis descended from pancreatic cancer. The onset of bowel metastasis is an event rarely associated with MPM, and has not been previously described in the literature for cases of pancreatic cancer. Therefore, to the best of our knowledge, the present study describes the first case of intestinal metastasis from pancreatic cancer in a long-term survival patient with biphasic MPM.

Comparative genetic analysis of a rare synchronous collision tumor composed of malignant pleural mesothelioma and primary pulmonary adenocarcinoma

Background

Although asbestos acts as a potent carcinogen in pleural mesothelial and pulmonary epithelial cells, it still remains unclear whether asbestos causes specific and characteristic gene alterations in these different kinds of target cells, because direct comparison in an identical patient is not feasible. We experienced a rare synchronous collision tumor composed of malignant pleural mesothelioma (MPM) and primary pulmonary adenocarcinoma (PAC) in a 77-year-old man with a history of long-term smoking and asbestos exposure, and compared the DNA copy number alteration (CNA) and somatic mutation in these two independent tumors.

Methods

Formalin-fixed paraffin-embedded (FFPE) tissues of MPM and PAC lesions from the surgically resected specimen were used. Each of these MPM and PAC lesions exhibited a typical histology and immunophenotype. CNA analysis using SNP array was performed using the Illumina Human Omni Express-12_FFPE (Illumina, San Diego, CA, USA) with DNA extracts from each lesion. Somatic mutation analysis using next-generation sequencing was performed using the TruSeq Amplicon Cancer Panel (Illumina).

Results

The CNA analysis demonstrated a marked difference in the frequency of gain and loss between MPM and PAC. In PAC, copy number (CN) gain was detected more frequently and widely than CN loss, whereas in MPM there was no such obvious difference. PAC did not harbor CNAs that have been identified in asbestos-associated lung cancer, but did harbor some of the CNAs associated with smoking. MPM exhibited CN loss at 9p21.2-3, which is the most common genetic alteration in mesothelioma.

Conclusion

In this particular case, asbestos exposure may not have played a primary role in PAC carcinogenesis, but cigarette smoking may have contributed more to the occurrence of CN gains in PAC. This comparative genetic analysis of two different lesions with same amount of asbestos exposure and cigarette smoke exposure has provided information on differences in the cancer genome related to carcinogenesis.

Small cell mesothelioma: A rare entity and diagnostic pitfall mimicking small cell lung carcinoma on fine-needle aspiration

Small cell mesothelioma (SCM) is an extremely rare variant of epithelioid mesothelioma that can be mistaken for other forms of small round blue cell tumors, particularly small cell lung carcinoma (SCLC). Here, we describe a fine-needle aspiration (FNA) from a pleural lesion in a 75-year-old man with a history of known asbestos exposure. The FNA revealed cohesive clusters of uniform small round blue cells with high nuclear-to-cytoplasmic ratio, finely powdery chromatin, small inconspicuous nucleoli, and scant amount of cytoplasm. Mitoses were infrequent and nuclear molding was absent. Immunochemical profile supported a mesothelial origin, which was later confirmed by pleurectomy with a diagnosis of SCM. This report demonstrates the difficulties in cytologic evaluation of lung FNAs in differentiating SCM from SCLC or other small round blue cell tumors. As therapy differs for SCM, early recognition of the cytologic features is essential in making the correct diagnosis needed for appropriate clinical management. Diagn. Cytopathol. 2016;44:526-529. © 2016 Wiley Periodicals, Inc.

Diffuse malignant mesothelioma and synchronous lung cancer: A clinicopathological study of 18 cases

OBJECTIVES

To examine the clinicopathologic characteristics of individuals with diffuse malignant mesothelioma (DMM) occurring concurrently with lung cancer (LC).

MATERIALS AND METHODS

A database of approximately 3800 patients with DMM was reviewed, from which 18 patients (0.5%) who had synchronous LC were identified. The clinicopathologic features, as well as the occupational exposure history and fiber burden analysis data were examined.

RESULTS

The patient median age was 68 years (range 58-84 years). Of the 18 patients (14 male, 4 female), 11 (61%) had epithelial, 5 (28%) had biphasic, and 2 (11%) had sarcomatoid DMM, with the majority (16 cases; 89%) originating in the pleura and only 2 were peritoneal. Among the histologic types of LC, adenocarcinoma was most frequent (12 cases; 67%), while 5 cases of squamous cell carcinoma, and 1 case of small cell carcinoma were observed. Three patients also had a history of prior malignancy (1 with testicular seminoma and bladder carcinoma and 2 with prostate carcinoma). Fifteen patients had a positive smoking history. All but 3 had documented asbestos exposure. Three had histologic features of asbestosis. Mineral analysis performed in 8 showed an elevated asbestos fiber burden in 4 (22%). Amosite was detected in 4 patients, crocidolite in 3, and non-commercial amphiboles in 5.

CONCLUSION

The finding of simultaneous carcinoma of the lung and DMM is distinctly unusual. The majority of patients are male smokers with pleural epithelial DMM and lung adenocarcinoma. This study represents the largest cohort of patients reported to date with synchronous malignant mesothelioma and lung cancer, and we propose guidelines for making a diagnosis of synchronous malignant mesothelioma and primary lung cancer.

Diagnostic utility of immunohistochemistry in distinguishing between epithelioid pleural mesotheliomas and breast carcinomas: a comparative study

Epithelioid mesotheliomas and breast carcinomas can present a variety of morphologic patterns. Because of this, breast carcinomas that metastasize to the pleura and lung may be confused with mesotheliomas. The aim of the present study is to compare the immunohistochemical markers currently available for the diagnosis of these 2 malignancies and to determine the best panel of markers that can be used to assist in discriminating between them. Sixty epithelioid mesotheliomas and 80 breast carcinomas (40 triple negative and 40 estrogen receptor positive) were investigated for expression of the positive mesothelioma markers calretinin, keratin 5/6, mesothelin, podoplanin, thrombomodulin, and WT1; the positive carcinoma marker claudin 4; and the breast-associated markers gross cystic disease fluid protein 15 (GCDFP-15), mammaglobin, and GATA3. All of the epithelioid mesotheliomas reacted for calretinin and keratin 5/6, 93% for WT1; 88% for podoplanin; 77% for thrombomodulin; 23% for GATA3; and 0% for claudin 4, GCDFP-15, and mammaglobin, respectively. Of the triple-negative breast carcinomas, 100% expressed claudin 4; 5%, keratin 5/6; 30%, GATA3; 18%, mammaglobin; 15%, GCDFP-15; 56%, mesothelin; 38%, calretinin; 18%, thrombomodulin; 5%, WT1; and 3%, podoplanin. Among the estrogen receptor-positive breast carcinomas, 100% were claudin 4 and GATA3 positive; 70% expressed GCDFP-15; 63%, mammaglobin; 13%, calretinin; 13%, thrombomodulin; 8%, WT1; 5%, keratin 5/6; 3%, mesothelin; and 0%, podoplanin. It is concluded that podoplanin and WT1 are the best positive mesothelioma markers for differentiating epithelioid mesotheliomas from breast carcinomas. An accurate differential diagnosis can be reached with the use of these two markers in combination with the breast-associated markers GCDFP-15, mammaglobin, and GATA3.

Collision tumors of hepatocellular carcinoma and malignant peritoneal mesothelioma

We report a case of synchronous hepatocellular carcinoma (HCC) and malignant peritoneal mesothelioma (MM-per). A 56-year-old man with no past history of asbestos exposure, chronic viral hepatitis, or alcoholic liver injury was admitted to our hospital with left flank pain and abdominal tumor. Partial hepatectomy, splenectomy, partial diaphragm resection, and partial gastrectomy were performed. The tumor in the lateral segment of the liver was gray to white, massive in appearance, and contained focal bile-producing nodules and extensive fibrous firm lesion. It had directly invaded the spleen and diaphragm. Liver cirrhosis was not found. The peritoneum contained multiple small nodules especially around the diaphragm, which mimicked carcinoma dissemination. After histological examination, the liver tumor was diagnosed as HCC. It had trabecular and scirrhous patterns and positive immunoreactivities for Hep-Par-1 and α-fetoprotein. The peritoneal nodules were diagnosed as MM-per, epithelioid type, with positive immunoreactivities for calretinin and cytokeratin 5/6. The two tumors collided around the diaphragm. Cases of MM synchronous with other primary malignant tumors have been reported, but most had a history of asbestos exposure unlike the present case. The carcinogenic background was unclear for two tumors in this case. This is an extremely rare and valuable case.

The use of immunohistochemistry in the diagnosis of composite and collision tumors: exemplified by pleural mesothelioma and carcinoid tumor of the lung

A case of a collision lymph node metastasis of a mesothelioma and a carcinoid tumor in a 73-year-old man with a history of asbestos exposure is reported. An interesting finding in this case was that both the mesothelioma and its lymph node metastases exhibited a wide variety of histologic patterns, including one characterized by a solid growth of large cells with abundant, clear, and foamy cytoplasm and another exhibiting deciduoid features. Pathologists should be aware that mesotheliomas can present very unusual morphologic features, such as those seen in the present case, and therefore, should be included in the differential diagnosis of those tumors that can display similar morphology and can metastasize to the serosal membranes. Reexamination of the pneumonectomy specimen in the current case identified a primary peripheral carcinoid tumor. The recognition of a nonasbestos-related tumor in a patient with mesothelioma is important since its presence may have an impact on the patient's life expectancy and, therefore, may affect any compensation settlement.

Ocular melanoma in a patient successfully treated for diffuse malignant peritoneal mesothelioma: a case report

Background

Diffuse malignant peritoneal mesothelioma and ocular melanoma are both rare tumors. To the best of our knowledge there is only one previous report of three cases in a family with known susceptibility to malignancies associating diffuse malignant peritoneal mesothelioma and ocular melanoma, with no sporadic cases previously reported.

Case presentation

We describe the case of a 59-year-old man with a history of diffuse malignant peritoneal mesothelioma, who presented with ocular melanoma 41 months after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. We also briefly review the literature.

Conclusions

Diffuse malignant peritoneal mesothelioma is an uncommon but aggressive disease. As diffuse malignant peritoneal mesothelioma characteristically remains confined to the abdominal cavity, any new extra-abdominal symptom should eventually raise suspicion of another primary tumor. Few cases of diffuse malignant peritoneal mesothelioma associated with other primary tumors have been reported. As ocular melanoma is also infrequent, we suspect a genetic predisposition to these tumors. There is emerging evidence supporting the role of BAP1 mutations in the pathogenesis of these two neoplasias.

Mesotheliomas with small cell features: report of eight cases

Mesotheliomas with small cell morphology are rare and only one study of such cases has been published. As a result of their rare occurrence, some investigators have cast doubt on the existence of such a histologic variant of mesothelioma. This investigator reports a series of eight cases of epithelioid mesothelioma with small cell features, all of which originated in the pleura. Seven of the patients were men and one was a woman. Four patients had a history of asbestos exposure. Histologically, four of the mesotheliomas were epithelioid and four biphasic. The proportion of small cells seen in these cases constituted 80 to 100% of the tumor included in the biopsy material and 15 to 20% of the tumor present in the pneumonectomy specimens. Immunoreactivity for calretinin, keratin 5/6, keratin 7, pan-keratin, WT1, podoplanin, and mesothelin was seen in all cases tested for these markers. All of the cases were negative for MOC-31, Ber-EP4, CEA, CD15, TAG-72, TTF-1, chromogranin A, synaptophysin, CD99, and desmin. The mean survival of the six patients for whom this information was available was 8.2 months. It is important for pathologists to be aware that mesotheliomas can present small cell features and, because of this, they can be confused with other malignancies that can exhibit similar morphology. The value of immunohistochemistry in the differential diagnosis of these tumors is discussed.

Problems in mesothelioma diagnosis

Many centres are now seeing increasing numbers of patients with malignant mesothelioma. This presents pathologists involved in making the diagnosis with a number of problems, which can be divided into those encountered in making the distinction between mesothelioma and benign changes and those experienced in separating mesotheliomas from other types of epithelial and connective tissue tumours. Immunohistochemistry plays a major role in helping to make the diagnosis, but it should be interpreted with due regard to the clinical setting and radiological features, and with a knowledge of the wide morphological variations seen in mesothelioma. This review identifies some of these problems and addresses the uses and limitations of immunohistochemistry in different situations. It includes a discussion of some of the less common variants of mesothelioma and other pleural-based tumours that enter into the differential diagnosis.

Malignant mesothelioma: global incidence and relationship with asbestos

Mesothelioma incidence varies markedly from one country to another. The highest annual crude incidence rates (about 30 cases per million) are observed in Australia, Belgium, and Great Britain. A lot of data indicate a relationship between mesothelioma and asbestos. The hot areas for mesothelioma exactly correspond to the sites of industries with high asbestos use, such as shipbuilding and asbestos-cement industry. However, in many countries with high asbestos consumption, mesothelioma incidence is low. The reasons for this fact are not clear. The latency periods elapsing between first exposure to asbestos and development of mesothelioma are mostly longer than 40 yr. An inverse relationship exists between intensity of asbestos exposure and length of the latency period. Mesothelioma generally develops after long-time exposures to asbestos. Some recent studies show that the risk increases with the duration of exposure. Possible co-factors in the pathogenesis of asbestos-related mesothelioma include genetic predisposition, diets poor in fruit and vegetables, viruses, immune impairment, recurrent serosal inflammation. The study of co-morbidity in mesothelioma could give an insight into the pathogenesis of the tumor. While a levelling-off in mesothelioma incidence has been registered in some countries, a worsening of the epidemic is predictable in large parts of the world.

Synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma

Synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma is rare. Cases from the archives of 2 large referral centers were reviewed to identify cases of synchronously occurring pulmonary carcinoma and pleural diffuse malignant mesothelioma. Three cases of synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma were identified from more than 16,000 pleuropulmonary cases and were reviewed for demographic, clinical, radiographic, histologic, and immunohistochemical findings. The patients were men who were 63, 67, and 77 years old. Two had positive smoking histories; the smoking history of the other patient is unknown. One patient had a positive history of asbestos exposure; one patient had no history of asbestos exposure; and one patient's history of asbestos exposure is unknown. The patients underwent surgery for treatment of adenocarcinoma that was diagnosed preoperatively. Two of the adenocarcinomas were of a predominantly bronchioloalveolar pattern. No diffuse malignant mesothelioma was identified preoperatively. Diffuse malignant mesothelioma was suspected on the basis of pleural involvement by tumor with histology differing from that of the adenocarcinoma. Tumor immunostaining supported the diagnoses. The average survival after diagnosis was 6 weeks or less. In summary, the paucity of cases at 2 large referral centers and the paucity of cases reported in the English language literature highlights the rarity of synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma. These synchronous neoplasms occur in patients who have risk factors for both neoplasms independently. Length of survival following diagnosis is bleak.

The diagnostic utility of immunohistochemistry in distinguishing between epithelioid mesotheliomas and squamous carcinomas of the lung: a comparative study

As both mesotheliomas and squamous carcinomas can present a wide variety of morphological patterns, they can on occasion be confused. Recently, some groups of investigators have called attention to the difficulties that sometimes exist in distinguishing between these malignancies and the need to define a panel of markers that can assist in reaching the correct diagnosis. The aim of the present study is to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and squamous carcinoma of the lung. A total of 30 epithelioid pleural mesotheliomas exhibiting a solid or predominantly solid pattern, and 30 nonkeratinizing squamous carcinomas of the lung were investigated for the expression of the following markers: podoplanin, calretinin, mesothelin, WT1, keratin 5/6, keratin 7, p63, carcinoembryonic antigen (CEA), MOC-31, Ber-EP4, B72.3, BG-8 (Lewis(y)), leu-M1 (CD15), and thyroid transcription factor-1 (TTF-1). All 30 (100%) of the mesotheliomas reacted for calretinin, mesothelin and keratin 7, 93% each for podoplanin, WT1 and keratin 5/6, 13% for Ber-EP4, 7% each for p63, MOC-31 and BG-8, and 0% for B72.3, CEA, leu-M1 and TTF-1. All 30 (100%) of the squamous carcinomas were positive for p63 and keratin 5/6, 97% for MOC-31, 87% for Ber-EP4, 80% for BG-8, 77% for CEA, 57% for keratin 7, 40% for calretinin and B72.3, 30% for leu-M1, 27% for mesothelin, 15% for podoplanin, and 0% for WT 1 and TTF-1. After analyzing the results, it is concluded that from a practical point-of-view, a combination of two positive mesothelioma markers (WT1 and calretinin or mesothelin) with two negative mesothelioma markers (p63 and MOC-31) would allow the differential diagnosis to be established between epithelioid mesotheliomas and squamous carcinomas of the lung in nearly all instances.

Extrapulmonary small cell carcinoma

This article reviews the recent literature on extrapulmonary small cell carcinomas. Until now, only four cases have been published in the English literature, two of those in the Southern Medical Journal. Sharing the information on diagnosis and treatment of these cases is important for better understanding and treatment of these patients. The differential diagnosis of pleural masses and the relation to asbestos exposure is briefly discussed. In addition, the available literature on other extrapulmonary localizations of small cell carcinoma is reviewed. The focus is on the available larger series of patients. Small cell carcinoma of the skin is included. This form of small cell carcinoma is often excluded from the larger review series, but can be an important alternative in the diagnostic process of patient evaluation.