Histochemical and ultrastructural features of an unusual pulmonary carcinosarcoma

Sarcomatoid Carcinoma of the Colon: A Case Report with Literature Review

Sarcomatoid carcinoma (SC) is a well defined tumor type that may occur in all organs and anatomic sites but most commonly in the head1, neck1, respiratory tract2-4, breast5, and genitourinary tract6-11. It is a biphasic tumor showing both epithelial- and mesenchymal-like differentiation; however, its carcinomatous nature is widely recognized12. SC is rare in the gastrointestinal tract. In the esophagus it accounts for less than 5% of all malignancies12-16 and approximately only 35 cases have been described in the stomach12,17-18. Very few cases have been observed in the small intestine19-20, anorectal junction21, liver22, and pancreas23-24. To our knowledge only eight cases of SC have been reported in the colon25-32. We report a case of primary colonic SC. Both morphological and immunohistochemical analyses are provided along with an evaluation of the unusual clinical history, therapeutic implications, and controversial differential diagnosis.

Sarcomatoid neoplasms of the lung and pleura

Sarcomatoid neoplasms of the lung and pleura are rare tumors that present a complex differential diagnosis, making them challenging for surgical pathologists. In the lung, the main tumors are the sarcomatoid carcinomas, including pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma, and pulmonary blastoma. They are characterized by histologic heterogeneity; molecular data support their origin from a pluripotent stem cell that undergoes neoplastic transformation with divergent epithelial and sarcomatous differentiation. Diagnosis is difficult in small biopsy specimens and typically requires a resection specimen. Despite the presence of sarcomatoid features, these tumors are classified as lung carcinomas. Pulmonary blastomas must be distinguished from pleuropulmonary blastomas, which are a unique type of thoracic sarcoma typically occurring in young children. In the pleura, the main tumors to consider are the sarcomatoid and desmoplastic types of malignant mesothelioma, solitary fibrous tumor, and desmoid tumor. While light microscopy is sufficient to diagnose most of these tumors, immunohistochemistry can be useful in selected settings. In particular, it can aid to confirm epithelial differentiation in spindle cell carcinomas and the presence of rhabdomyosarcoma in sarcomatoid carcinomas, mesotheliomas, or pleuropulmonary blastomas. For sarcomatoid and desmoplastic mesothelioma, keratin is the most useful stain because it can highlight invasive growth and mesothelial markers are positive in only the minority of cases. Clinical and radiologic correlation is needed to separate some pleomorphic carcinomas with pleural involvement from sarcomatoid malignant mesothelioma, since these poorly differentiated tumors may not express the usual immunohistochemical markers for carcinoma or mesothelioma.

Review article: pulmonary sarcomatoid carcinomas: a practical overview

Pulmonary sarcomatoid carcinomas (PSCs) are currently defined as poorly differentiated non-small-cell carcinomas containing a component with sarcoma or sarcoma-like (spindle and/or giant cell) features. They consist of 5 major histological variants, namely pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma, and pulmonary blastoma. The segregation of PSCs into a distinct clinicopathologic entity seems justified on the basis of morphologic, behavioral, and genotypic/phenotypic attributes. As a group, PSCs generally run an aggressive clinical course and may cause major difficulties in the differential diagnosis with other primary and secondary malignancies of the lung. At present, PSCs are believed to represent a family of carcinomas "in transition," in which diverse pathways of clonal evolution account for histological differences of a common ancestor lesion. The sarcomatous or sarcomatoid component of these tumors is thought to derive from carcinoma cells during the progression of carcinogenesis through the activation of an epithelial-mesenchymal transition program leading to sarcomatous transformation or metaplasia (conversion paradigm). Conceivably, targeting the epithelial-mesenchymal transition program could become a valid therapeutic strategy for these life-threatening tumors, whose sensitivity to current medical manipulation is disappointing.

Evidence for colorectal sarcomatoid carcinoma arising from tubulovillous adenoma

Sarcomatoid carcinomas of the colorectum are rare tumors that display both malignant epithelial and stromal components. Clinically, they are aggressive tumors with early metastasis. Due to their infrequent occurrence, the pathogenesis is poorly understood. We report a case of a 52-year-old woman who presented with a rectal mass and intermittent hematochezia. Superficial biopsies during colonoscopy revealed a tubulovillous adenoma with high-grade dysplasia. Endoscopic ultrasonography confirmed an invasive nature of the mass, and deeper biopsies revealed the presence of neoplasm with mixed histological components. The surgically-excised specimen demonstrated the presence of poorly differentiated spindle cells underneath the tubulovillous adenoma and an intermediate stage of invasive adenocarcinoma. Based on the histological appearance and immunohistochemical studies, a diagnosis of sarcomatoid carcinoma was made. Only nine cases of sarcomatoid carcinomas of the colorectum have been reported to date. As a result, the terminology and pathogenesis of sarcomatoid carcinoma remain speculative. To the best of our knowledge, this is the first report of co-existence of sarcomatoid carcinoma and invasive adenocarcinoma with tubulovillous adenoma; all stages represented within the same tumor. This observation supports the “monoclonal theory” of pathogenesis with an adenoma-sarcoma progression with or without an intermediate stage of carcinoma.

Nodular glomeruloid pleuroblastoma: a biphasic pleural-based malignant tumor with immature elements

An unusual diffuse pleural-based tumor arising in an elderly asbestos-exposed male is presented. The tumor presented in a 72-year-old male with a 30-year history of dockyard work and likely significant asbestos exposure. Macroscopically, at post mortem, the pleural tumor diffusely encased the right lung and was composed of an admixture of neoplastic macro-, and by light microscopy, micro-nodules. Histologically, the tumor had a biphasic growth pattern with glomeruloid epithelioid elements and immature blastematous mesenchymal stroma. Immunophenotypically, the tumor had a complex pattern with epithelioid elements expressing cytokeratins, desmin, carcinoembryonic antigen (CEA), Ber EP4 and E-cadherin. The diagnostic problems and medicolegal issues surrounding the diagnosis and differentiation from malignant pleural mesothelioma and other tumors are discussed.

Metaplastic carcinoma of the breast with rhabdomyosarcomatous element: aspiration cytology with histological, immunohistochemical, and ultrastructural correlations

We studied a metaplastic breast carcinoma with a rhabdomyosarcomatous element from a 62-yr-old woman. In the fine-needle aspirates processed by Ultrafast Papanicolaou stain, there were small undifferentiated cells with scanty cytoplasm and differentiated cells with red macronucleoli and abundant cytoplasm. Some differentiated cells contained a brown inclusion with a blue rim. Ultrastructurally, the brown inclusion correlated to a central aggregate of sarcomeres and the blue rim correlated to actin filaments surrounding the sarcomeres. The differentiated cells without cytoplasmic inclusions expressed cytokeratin and contained tonofilaments. A transitional cell type containing both sacromeres and tonofilaments was absent. Immunohistochemically, the small undifferentiated cells expressed vimentin diffusely and showed >90% MIB-1 proliferating index, whereas the differentiated cells expressed cytokeratin, actin, or myoglobin and had virtually absent MIB-1 nuclear labeling. Histologically, the small cells were more concentrated along the capsule and the large cells were more concentrated in the center of the tumor. These findings suggest the bidirectional differentiation of the small undifferentiated cells into carcinoma cells and rhabdomyosarcoma cells in this tumor.

Molecular pathogenesis of pulmonary carcinosarcoma as determined by microdissection-based allelotyping

Pulmonary carcinosarcoma is a rare, biphasic tumor composed of malignant epithelial and mesenchymal elements. Its histogenesis is controversial in light of the presence of divergent cell lineages and the clonal nature of malignancy. To address these issues, we performed an extensive comparative genotypic analysis using microdissection to secure representative mesenchymal and epithelial components from each of six cases of pulmonary carcinosarcoma. Loss of heterozygosity was analyzed with a panel of 12 polymorphic microsatellite markers designed to indicate allelic loss and situated in proximity to known tumor suppressor genes located on 1p, 3p, 5q, 9p, 10q, and 17p. In accordance with the relatively greater biologic aggressiveness of this tumor type, both the epithelial and mesenchymal components showed extensive allelic loss, most notably for 3p, 5q, and 17p. More importantly, we found overall equivalent patterns of acquired allelic loss between the two components on an individual case basis, strongly supporting the monoclonal origin of these neoplasms. Minor differences in the allelic fingerprint between the two cell lineages could be explained by progressive accumulation of allelic loss alterations that appear to occur more frequently in the mesenchymal component of the tumor. The data support the efficacy of microdissection-based allelic fingerprinting to delineate the relationship between different morphologic components of a single neoplasm.

Small cell neuroendocrine carcinoma with skeletal muscle differentiation: report of three cases

Three cases of neuroendocrine carcinoma showing skeletal muscle differentiation are presented. The tumors were located in the skin and subcutaneous tissue, the urinary bladder, and the nasal cavity respectively, and were composed by two cell types admixed intimately with each other. One cell type had features identical to those seen in conventional small cell neuroendocrine carcinoma, including scanty cytoplasm, round nuclei with fine granular chromatin, immunohistochemical reactivity for neuron-specific enolase, chromogranin and cytokeratins, and electron-dense granules on ultrastructural examination. The second cell type was either plasmacytoid or elongated and straplike, with abundant eosinophilic cytoplasm and irregular nuclei with prominent nucleoli. These cells showed immunohistochemical positivity for desmin, sarcomeric actin, myoglobin, and myogenin. They also exhibited ultrastructural evidence of rhabdomyoblastic differentiation in the form of contractile filaments with abortive Z-band formation. An origin from a cell capable of dual differentiation toward neuroendocrine and rhabdomyoblastic elements is postulated for these tumors.

Carcinosarcomas of the lung: a clinicopathologic study of 66 patients

Carcinosarcoma is a malignant tumor having a mixture of carcinoma and sarcoma containing differentiated mesenchymal elements, such as malignant cartilage, bone, and skeletal muscle. These tumors have been linked histogenetically to pleomorphic carcinomas; it is unclear whether their clinical behavior is significantly different. To investigate this issue, we studied 66 cases of carcinosarcomas of the lung and compared them with cases from a previously published series of pleomorphic carcinomas. Carcinosarcomas show a male-to-female ratio of 7.25:1, with a mean and median age of 65 years. They most often present as solitary masses in the upper lobes and average 7 cm in diameter. Most (62%) were endobronchial or central tumors, whereas 38% were described as peripheral. The most frequent epithelial component was squamous cell carcinoma (46%), followed by adenocarcinoma (31%) and adenosquamous carcinoma (19%), whereas sarcomatous elements most frequently included rhabdomyosarcoma, chondrosarcoma, osteosarcoma, or combinations of these elements. Survival of patients with carcinosarcomas of lung was poor, with a 5-year survival rate of 21.3%. Of several clinical and pathologic parameters, only increased tumor size (with 6 cm as the optimal cutoff point) appeared to be related to reduced survival (p = 0.0195). In comparison with patients with pleomorphic carcinoma, patients with carcinosarcomas had no significant difference in the size of their tumors (p = 1.0), stage at presentation (p = 0.883), location in the lung (p = 0.073), or their overall survival (21.3% vs 15.0%) (p = 0.1038). A significantly greater proportion of patients with carcinosarcoma had squamous cell (p = 0.004) or adenosquamous (p = 0.016) carcinoma, whereas patients who had pleomorphic carcinoma showed a significantly greater frequency of adenocarcinoma (p = 0.029) and large cell carcinoma. The histologic differences between these two types of tumor suggest that they may be different entities with similar behavior, but additional studies are warranted to investigate this hypothesis.

Pulmonary carcinosarcoma: immunohistochemical and ultrastructural studies

A case of pulmonary carcinosarcoma in a 68-year-old male patient is reported. The tumor in the resected left upper lobe extended mainly endobronchially, invading the normal bronchial lumina and mucosa. The carcinomatous component consisted of poorly differentiated squamous cell carcinoma and was mainly located in the periphery of the tumor nests. The sarcomatous component consisted of chondrosarcoma and was mainly located in the center of the tumor nests. Tumor cells in the sarcomatous component reacted with anti-S-100 protein antibody and were surrounded with abundant homogeneous extracellular matrix staining positively with Alcian blue. The transition from the carcinomatous component to the sarcomatous component appeared to be very smooth. The tumor cells in both the carcinomatous and sarcomatous components reacted with anti-epithelial membrane antigen antibody. Ultrastructurally, the tumor cells with tonofibrils in the carcinomatous component were apposed and connected to each other by desmosomes. By contrast, in the sarcomatous component, the tumor cells had well-developed and dilated rough endoplasmic reticulum and were arranged loosely in a myxomatous matrix. Some tumor cells in the sarcomatous component had occasional tonofibrils, and were apposed and connected to each other by desmosome-like structures. It is shown for the first time, ultrastructurally and immunohistochemically, that the tumor cells in the sarcomatous component of pulmonary carcinosarcomas have features of both epithelial and mesenchymal cells. It is suggested that the sarcomatous component in the present case is derived from the carcinomatous component.

Sarcomatoid carcinoma: an ultrastructural study with light microscopic and immunohistochemical correlation of 10 cases from various anatomic sites

The histogenesis of sarcomatoid carcinoma has been an intriguing topic for pathologists for many years, and considerable evidence has accumulated in the fields of tissue culture, electron microscopy, and immunohistochemistry to support the concept that the sarcomatous cells derive by way of "divergent differentiation" (metaplasia) from the carcinomatous elements. We have studied a group of 10 cases of these tumors from various organs, using detailed ultrastructural analysis as well as light microscopic and immunohistochemical correlation. We found that there is an ultrastructural spectrum of differentiation from epithelial to mesenchymal type features and that the malignant spindle cells may be purely epithelial (3 cases), purely mesenchymal (3 cases), or a mixture of both (4 cases). Furthermore, individual cells may show biphasia, having desmosomes and tonofibrils as well as well developed rough endoplasmic reticulum and filaments with dense bodies. Electron microscopic and immunohistochemical results do not always correlate, illustrating the prudence of using several keratin antibodies, including wide-spectrum ones, and of performing electron microscopic examination on these tumors.

A case of adenocarcinoma of the lung with a spindle cell component

We report a 60-year-old man, who was admitted to the hospital with complaints of cough and sputum. His chest x-ray showed an abnormal mass in the right upper lobe. After admission he noticed the painful gingival tumor. Right upper lobectomy and resection of the gingival tumor were performed. Their histological features showed that the tumor consisted of a papillary and tubular adenocarcinoma mixed with a component of spindle cells. Immunohistochemical study demonstrated a positive reaction in the epithelial component for keratin and epithelial membrane antigen, and not only these epithelial markers but also vimentin were expressed in some spindle tumor cells. Electron microscopic study confirmed the biphasic pattern, showing gland formation and undifferentiated cells. We diagnose this case as adenocarcinoma of the lung with a spindle cell component and the gingival tumor was metastatic. Autopsy showed that metastatic lesions were found in the left adrenal gland and in the left kidney. The tumor cells in the left adrenal gland were composed of spindle cells and the tumor in the left kidney showed gland formation. Immunohistochemical and electron microscopic findings of surgical and autopsy specimen suggest that this tumor is of epithelial origin, and the spindle cells are derived from immature mesenchymal cell transformation of epithelial cells.

Carcinoma of the vulva with sarcomatoid features: a case report with immunohistochemical study

A tumor of the vulva with sarcomatoid features was studied by immunocytochemistry to characterize the phenotype of the spindle-shaped and giant cells. Sarcomatoid-looking cells were positive for intermediate filament keratin polypeptides of stratified epithelium. These results favor histogenesis of the sarcomatoid-looking cells from a metaplastic alteration of the malignant squamous component.

An immunohistological comparison of primary lung carcinosarcoma and sarcoma

We wished to assess the antigenic expression of primary lung tumors diagnosed as either carcinosarcoma or sarcoma in order to determine whether this information would be useful in distinguishing the two. We therefore immunohistochemically analyzed six pulmonary carcinosarcomas and five primary lung sarcomas for the presence of carcinoembryonic antigen (CEA), S100 protein, cytokeratin and vimentin using commercially available monoclonal and polyclonal antibodies on formalin fixed tissues. Six of six carcinosarcomas stained positively for cytokeratin while none of the sarcomas stained. In three carcinosarcomas both the carcinomatous and sarcomatous areas were positive while in three only the carcinomatous areas were positive. CEA staining was present in five carcinosarcomas and absent in all the sarcomas. CEA positivity was strong and not confined to those tumors with obvious gland formation. Staining for S100 protein was positive in two carcinosarcomas but only in those areas showing chondroid differentiation. Immunohistochemical staining for vimentin using two different monoclonal antibodies gave inconsistent results. We conclude that in differentiating between a carcinosarcoma and a sarcoma of the lung, immunohistochemical staining for both cytokeratin and CEA are useful with cytokeratin marginally preferable. The data indicate that carcinosarcoma of the lung, like that of the upper aerodigestive tract, expresses antigens suggesting both epithelial and mesenchymal differentiation.

Pulmonary carcinomas with a sarcomatoid element: an immunocytochemical and ultrastructural analysis

Eight primary carcinomas of the lung with a prominent spindle-cell sarcomatoid component were studied by immunocytochemical staining and electron microscopy. The eight tumors were indistinguishable by conventional light microscopy, with the exception of one unusual neoplasm that followed multiple pathways of differentiation with elements of squamous cell carcinoma, rhabdomyosarcoma, chondrosarcoma, and an undifferentiated spindle-cell population. Reticulin fiber production by individual spindle cells and a sharp demarcation of the carcinomatous and sarcomatoid domains by light microscopy were not useful differentiating features. Three of the eight tumors exhibited keratin expression in both the carcinomatous and spindle-cell components. Both immunocytochemical and electron microscopic analyses were required to detect epithelial differentiation, as in one case keratin was identified only by immunocytochemical staining and in another only by ultrastructural examination. Epithelial differentiation was undetectable in the sarcomatoid component of five tumors, and in one case immunoreactive myoglobin was identified in spindle cells; skeletal muscle differentiation was confirmed ultrastructurally. We propose that pulmonary carcinomas exhibiting evidence of epithelial differentiation in a sarcomatoid component be termed spindle-cell carcinomas and that those biphasic tumors exhibiting mesenchymal differentiation into specific tissues, such as neoplastic bone, cartilage, or striated muscle, or lacking epithelial differentiation by light microscopy, immunocytochemistry, and electron microscopy be classified as carcinosarcomas. This distinction may ultimately be unnecessary, because these two tumors may represent different points along a morphologic and biologic continuum.

Carcinosarcoma of the colon. Report of a unique case with light and immunohistochemical studies

A unique case of carcinosarcoma of the colon is reported. The tumor invaded the bowel wall deeply, metastasized widely, resisted multi-agent chemotherapy, and caused the patient's death 4 years later. The tumor was composed of adenosquamous carcinoma admixed with sarcoma showing osseous, cartilaginous, and nonspecific spindle-cell differentiation. Although carcinoembryonic antigen appeared limited to carcinoma cells, cytokeratin immunoreactivity was observed in both carcinoma and sarcoma cells. Like carcinosarcomas at other body sites, the finding of cytokeratin in sarcoma cells supports partial epithelial differentiation in this component, likely retained from carcinoma precursor cells.

Carcinosarcoma of the lung with spindle-cell epithelial component: report of a case

A case of primary endobronchial carcinosarcoma with predominant spindle cell squamous carcinoma is described. The spindle cell component has not been previously reported as occurring in pulmonary carcinosarcomas. We suggest that this variety of carcinosarcoma closely resembles sarcoma of the lung histologically and emphasize that a distinction between the two neoplasms is important in view of the generally good prognosis of endobronchial carcinosarcomas.