Gastric adenocarcinoleiomyosarcoma: a light, electron microscopic and immunohistological study

Gastrointestinal stromal tumors (GISTs) and synchronous intra-abdominal malignancies: case series of a single institution's experience

Background: Gastrointestinal stromal tumors (GISTs) quite often co-exist with other primary tumors, as seen in up to 33% of cases. In the literature such occurrences have primarily been described through case reports and rarely through case series, which is not sufficient to prove if there is an association between these two entities.

Materials and Methods: We conducted a retrospective study using medical and pathological records from sixty-nine patients who underwent surgical treatment for GIST in a single university surgical department between 2011 and 2019. Seven cases of GIST accompanying a synchronous primary tumor were identified and included in the study.

Results: Survival analysis comparing the overall survival of patients with single GIST versus patients with concurrent GIST and another primary tumor, has shown no statistically significant difference between these two groups (p = 0.19). However, when comparing the recurrence rate, patients with synchronous GISTs and another primary tumor have a statistically significant increased possibility for recurrence (p = 0.02). Statistical analysis comparing the size of GISTs between the two groups has shown that patients with single GIST have larger tumors than patients with synchronous tumors (p = 0.048).

Conclusions: The synchronous occurrence of GISTs and other intra-abdominal tumors is more common than previously considered, though it is not yet clear if there is a causal association for the concomitant occurrence. Further studies are required to elucidate the genetic and molecular mechanisms of carcinogenesis and progression associating GIST and synchronous tumors.

Adenocarcinosarcoma at the esophagogastric junction with long esophageal invasion: a case report

BACKGROUND

Carcinosarcoma of the esophagus or esophagogastric junction (EGJ) is a rare malignancy with both carcinomatous and sarcomatous components. There is no report of carcinosarcoma arising from the EGJ wherein the carcinomatous element was adenocarcinoma. We describe a patient with carcinosarcoma of the EGJ in which the carcinomatous element was adenocarcinoma.

CASE PRESENTATION

A 52-year-old man was diagnosed with carcinoma on his EGJ after complaining of appetite loss. All tumor markers (carcinoembryonic antigen, squamous cell carcinoma antigen, alpha-fetoprotein, and carbohydrate antigen 19-9) were within the respective normal ranges. Esophagogastroduodenoscopy showed a 150-mm (100 mm esophageal side and 50 mm gastric side) type 1 tumor on his EGJ. A histopathological examination of a biopsy specimen revealed well-differentiated tubular adenocarcinoma at the gastric side; however, only necrotic tissue was noted on the esophageal side. Contrast-enhanced computed tomography did not reveal any invasion of the adjacent structures; however, it did show five swollen regional lymph nodes. ¹⁸F-Fluorodeoxyglucose positron emission tomography with computed tomography did not reveal distant metastases. We performed thoracic subtotal esophagectomy, total gastrectomy, and two-field plus left cervical paraesophageal lymphadenectomy. Macroscopically, the lesion consisted of two components: a 7.5-cm type 2 tumor and a 9-cm type 1 tumor at the proximal end of the type 2 tumor. Microscopically, the type 2 tumor showed predominantly solid or cribriform proliferation of tumor cells with clear cytoplasm, which was moderately differentiated adenocarcinoma with enteroblastic-like differentiation. The tumor cells of the adenocarcinoma component had periodic acid-Schiff (PAS)-positive globules and were positive for sal-like protein 4 (SALL 4) and negative for α-fetoprotein (AFP) or human epidermal growth factor receptor type 2 (HER2). The type 1 tumors consisted of the adenocarcinoma-like type 2 tumor and spindle cells (sarcomatous component). Part of the sarcomatous component showed cartilage differentiation. The type 2 and type 1 lesions were continuous lesions. The epicenter of the tumor was located at the EGJ. The adenocarcinoma component was present in 10 of 27 resected lymph nodes. The tumor was diagnosed as carcinosarcoma of the EGJ.

CONCLUSIONS

We report a rare patient with carcinosarcoma of the EGJ wherein the carcinomatous element was adenocarcinoma.

Carcinosarcoma of the Stomach with Endocrine Differentiation. A Case Report

An unusual tumor was observed In a 67-year-old man. Microscopically, the tumor was composed of epithelial cells forming glands (CEA, EMA-positive) and spindle-shaped cells (vimentin-positive). A third component was a cell population ultrastructurally characterized by intracytoplasmic granules surrounded by a membrane; these proved to be chromogranin A-positive in the immunoperoxidase study.

Clinicopathological and molecular characteristics of synchronous gastric adenocarcinoma and gastrointestinal stromal tumors

Synchronous gastric tumors that consist of both gastrointestinal stromal tumor (GIST) and adenocarcinoma are rare. We studied the clinicopathological and molecular characteristics of six cases containing both gastric adenocarcinoma and GIST. By means of immunohistochemical analysis, all GIST cells expressed CD117, CD34 and Dog1 in all six synchronous gastric adenocarcinomas with GIST, and in GIST alone. Sequencing analysis demonstrated that exon 11 c-kit mutations were present in two of six synchronous tumors and four of five GISTs. One of the two exon 11 c-kit mutations in synchronous adenocarcinomas with GISTs was an uncommon mutation of CTT > CCA at amino acid 576, and the other was a GTT deletion at amino acid 560. The mutation was a homozygous A > G mutation in exon 12 (amino acid 567) of PDGFR-α. We concluded that the exon 11 mutations were the most important in both cases of synchronous gastric adenocarcinoma with GIST and GIST alone. The mutation rate was higher in GIST alone than in synchronous adenocarcinoma with GIST.

Gastric carcinosarcoma with rhabdomyosarcomatous differentiation: a case report and review

We report an unusual case of gastric carcinosarcoma with rhabdomyosarcomatous and neudoendocrinal differentiation in a 71-year-old Japanese female. Gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation is a rare tumor. The tumor developed in the body of the stomach and was exophytic in appearance. By histochemical analysis, the tumor was shown a part of positive for desmin and myoglobin and a part of positive for synaphtophysin and vimentin.We conclude that, though rare, gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation thus is reviewed in the English literatures.

Synchronous adenocarcinoma and gastrointestinal stromal tumors in the stomach

AIM: To review the clinicopathological characteristics of concurrent gastrointestinal stromal tumors (GISTs) and gastric adenocarcinoma.

METHODS: We retrospectively analyzed eight cases of synchronous adenocarcinoma and GIST in the stomach that had been surgically resected with curative intent between March 2003 and December 2008 in Xinhua hospital and Ruijin hospital. The adenocarcinoma was determined to be the primary tumor based on the histological features. The GIST cells were diffusely and strongly positive for CD34 and CD117.

RESULTS: The patients were six men and two women aged 47-80 years (average, 68.6 years). GIST was preoperatively detected in only one patient. The average sizes of the gastric adenocarcinomas and GISTs were 6.000 ± 2.6186 cm and 1.825 ± 1.4370 cm, respectively. All GISTs were very low- or low-risk lesions that were detected during evaluation, staging, operation or follow-up for gastric adenocarcinoma.

CONCLUSION: We hypothesized that the stomach was influenced by the same unknown carcinogen, resulting in a simultaneous proliferation of different cell lines (epithelial and stromal cell).

Rapidly deforming gastric carcinosarcoma with osteoblastic component: An autopsy case report

Carcinosarcomas are rare, malignant, biphasic tumors simultaneously comprising carcinoma and sarcoma in a single tumor. We present an extremely rare case of gastric carcinosarcoma with an osteoblastic component that drastically changed its shape within 2 mo. A 59-year-old male patient presented to the emergency outpatient unit with a complaint of black stool. Gastrointestinal endoscopy showed an ulcerated mass in the cardia of the lesser curvature of the stomach. Biopsy specimens revealed only adenocarcinoma. Two months later, the ulcerated lesion drastically changed its shape into an exophytic tumor. Total gastrectomy was performed. In the resected specimen, the gastric tumor contained both adenocarcinoma and sarcoma components with lace-like osteoid. The patient died 7 mo after the operation, and an autopsy was performed. In the autopsy, widespread metastases were present in the liver, lung, lymph nodes and peritoneum. In this report, we describe a case of gastric carcinosarcoma and presume its tumorigenesis based on the autopsy findings.

Collision tumor of the stomach: gastric adenocarcinoma intermixed with gastrointestinal stromal tumor

The synchronous occurrence of tumors of different histological types in the stomach is uncommon. This rare association is usually detected incidentally at gastroscopy, surgery or histopathology. It is still not known whether such association represents an incidental coexistence or indicates a similar pathogenesis in the simultaneous development of tumors of different histological types in the same organ. A 73-year-old woman complained of discomfort after eating a Chinese dumpling, and had tarry stools three times. Gastroscopy showed a tumor at the juncture of the gastric fundus and corpus. The tumor was composed of gastric adenocarcinoma and gastrointestinal stromal tumor, in which the two components were intermixed with each other. To the authors' knowledge there are few reports of this extremely rare collision tumor association.

A distinctive novel epitheliomesenchymal biphasic tumor of the stomach in young adults ("gastroblastoma"): a series of 3 cases

This report describes 3 cases of a distinctive, hitherto unreported gastric epitheliomesenchymal biphasic tumor that differs from other biphasic tumors of the stomach and elsewhere: carcinosarcoma, biphasic synovial sarcoma, teratoma, and mixed tumor. The tumors occurred in young adults, 2 males and 1 female, of ages 19, 27, and 30 years. Two tumors were located in the greater curvature in the gastric body and one in the antrum. The tumors measured 5, 6, and 15 cm in maximum diameter, and their mitotic rates were 0, 4, and 30 mitoses per 50HPF. There were 2 components: uniform oval or spindled cells in diffuse sheets, and clusters or cords of epithelial cells occasionally forming glandular structures with small lumens. The epithelial elements were positive for keratin cocktail AE1/AE3, keratin 18, and partly for keratin 7, but were negative for keratins 5/6, 20 and epithelial membrane antigen. The spindle cells were positive for vimentin and CD10. All components were negative for CD34, CD99, estrogen receptor, KIT, smooth muscle actin, desmin S100 protein, p63, calretinin, chromogranin, synaptophysin, CDX2, and thyroid transcription factor 1. In situ hybridization for SS18 rearrangement was negative in all cases separating this tumor from synovial sarcoma. All 3 patients were alive after follow-up of 3.5, 5, and 14 years. Because these tumors have some resemblance to blastomas of other organs, we propose the term "gastroblastoma" for this distinctive, at least low-grade malignant epitheliomesenchymal tumor of the stomach.

Gastric carcinosarcoma presenting as a huge epigastric mass

Gastric carcinosarcoma often presents with an elevated lesion or increased thickness of the stomach wall. Histological diagnosis is achieved using conventional hematoxylin and eosin staining to confirm the coexistence of both epithelial and mesenchymal elements. We report a case of gastric carcinosarcoma presenting as a large mass in the epigastric region. Specimens obtained by endoscopic biopsy and surgical excision showed diffuse proliferation of atypical cells in sheet formation. No mucus production or glandular structures were apparent, but immunoreactivity for both epithelial and mesenchymal markers was noted. These findings led to a definitive diagnosis of gastric carcinosarcoma. Immunohistochemical analysis is useful for the early diagnosis and treatment of gastric carcinosarcoma.

Gastric carcinosarcoma presenting as a huge epigastric mass

Gastric carcinosarcoma often presents with an elevated lesion or increased thickness of the stomach wall. Histological diagnosis is achieved using conventional hematoxylin and eosin staining to confirm the coexistence of both epithelial and mesenchymal elements. We report a case of gastric carcinosarcoma presenting as a large mass in the epigastric region. Specimens obtained by endoscopic biopsy and surgical excision showed diffuse proliferation of atypical cells in sheet formation. No mucus production or glandular structures were apparent, but immunoreactivity for both epithelial and mesenchymal markers was noted. These findings led to a definitive diagnosis of gastric carcinosarcoma. Immunohistochemical analysis is useful for the early diagnosis and treatment of gastric carcinosarcoma.

Gastric carcinosarcoma with neuroendocrine differentiation as the carcinoma component and leiomyosarcomatous and myofibroblastic differentiation as the sarcomatous component

Gastric carcinosarcoma with neuroendocrine differentiation is a very rare neoplasm. In this article we present such a case. The gastroendoscopic examination of a 59-year-old Japanese man disclosed gastric cancer during follow-up after operation for rectal cancer. Subsequently, total gastrectomy was carried out because of gastric cancer. A large tumor measuring 9.2 x 8.4 cm was observed in the posterior wall of the upper portion of the stomach. The tumor was composed of carcinoma and sarcomatous cells, and the histological transition of both components was observed. Immunohistochemically, carcinoma and sarcomatous cells were positive for cytokeratin CAM5.2. The carcinoma contained adenocarcinoma and malignant cells with neuroendocrine differentiation. The sarcomatous component showed leiomyosarcomatous and myofibroblastic differentiation. The present tumor is the fifth case of gastric carcinosarcoma with neuroendocrine differentiation and the first case of gastric carcinosarcoma with myofibroblastic differentiation. Pathologists should bear in mind that gastric carcinosarcoma may show various types of differentiation.

Carcinosarcoma (pure endocrine cell carcinoma with sarcoma components) of the stomach

A case of gastric carcinosarcoma with a rare histology is reported. Grossly, a huge ulcerative tumor (Borrmann type 3 tumor, measuring 10 x 6 cm) was observed on the lesser curvature side of the stomach. Microscopically, the tumor consisted of carcinoma and sarcoma components. The main tumor component consisted of an endocrine cell carcinoma exhibiting positive reactions for cytokeratins, chromogranin A, synaptophysin, and CD56. The sarcoma component occupied less than 10% of the entire tumor area and consisted of spindle cells, some of which showed a rhabdomyosarcoma differentiation. Some of the spindle cells also showed an atypical cartilage or osseous differentiation. This sarcoma component exhibited positive staining not only for vimentin and desmin, but also for cytokeratins. Transitions between these two components were occasionally observed. These findings suggest that the sarcoma component in our case most likely originates from the endocrine cell carcinoma component.

Collision tumor of the stomach: a case report of mixed gastrointestinal stromal tumor and adenocarcinoma

Collision tumors of the stomach are uncommon. To the best of our knowledge, this is the first case report of gastric collision tumor composed of gastrointestinal stromal tumor (GIST) intermixed with primary adenocarcinoma in the English literature. The adenocarcinoma was determined to be the primary tumor based on histologic features. The tumor cells of the GIST were diffusely and strongly positive for CD34 and CD117, weakly positive for smooth muscle actin (5% of cells), and negative for desmin, S-100 protein, synaptophysin, and cytokeratin. There was no transition between the different components. We hypothesized that the stomach was influenced by the same unknown carcinogen, resulting in a simultaneous proliferation of different cell lines (epithelial and stromal cell). This case represents an example of two independent tumors in a unique one-on-another pattern, namely growth of adenocarcinoma on GIST.

Synchronous occurrence of epithelial and stromal tumors in the stomach: a report of 6 cases

OBJECTIVE

The synchronous development of epithelial and stromal tumors in the stomach has been reported rarely in the literature. A series of 6 such cases is described in this article.

METHODS

Clinical and pathologic data were recorded and the literature was reviewed.

RESULTS

Five cases featured the simultaneous occurrence of stromal tumors (1 benign, 3 borderline, 1 malignant) and adenocarcinomas, whereas the stromal tumor in the sixth case was found in association with a carcinoid. No collision tumors were observed. In 2 cases, tumors arose from the same site and were closely juxtaposed, but in 4 patients they developed from different areas of the stomach. A preoperative histologic diagnosis of both tumors was not achieved in any case. Two patients harbored occult infiltrative epithelial lesions (1 diffuse-type adenocarcinoma, 1 carcinoid), which were detected only at pathologic examination of the gastric mucosa adjacent to the stromal tumor.

CONCLUSIONS

The simultaneous occurrence of epithelial and stromal tumors in the stomach can be less rare than usually expected. Coincidence alone could account for such an association, particularly in areas with high incidence rates of gastric cancer. The hypothesis that a single carcinogenic agent might interact with two neighboring tissues in the stomach inducing the development of tumors of different histotype cannot be theoretically discarded.

Synovial sarcoma of the upper digestive tract: a report of two cases with demonstration of the X;18 translocation by fluorescence in situ hybridization

Two cases of synovial sarcoma that arose in the upper digestive tract are reported. One case was a polypoid mass that arose at the gastroesophageal junction; the other was a large intramural mass that arose in the wall of the stomach. Both cases had a classic biphasic pattern. In the stomach tumor, the biphasic morphology was focal and there was an abrupt transition to poorly differentiated synovial sarcoma. The tumors had immunohistochemical features that were consistent with synovial sarcoma. Ultrastructural evaluation of the gastroesophageal tumor supported the diagnosis. The diagnostic X;18 translocation was demonstrated by fluorescence in situ hybridization on sections from paraffin-embedded tissue in 86% and 50% of interphase nuclei from the gastroesophageal and gastric tumor, respectively. The translocation was present in equal frequency in the epithelial and spindle cells in the biphasic areas and the poorly differentiated areas of the gastric tumor, indicating that the development of the more aggressive subclone was probably due to genetic mutations not encompassing the SYT-SSX gene fusion product. We are aware of only five reported cases of synovial sarcoma arising in the digestive tract, all in the proximal esophagus. These cases are the first reported arising in the gastroesophageal junction and stomach and the only cases of synovial sarcoma of the digestive tract in which the diagnostic translocation was demonstrated. Sarcomatoid carcinoma (carcinosarcoma) and gastrointestinal stromal tumor are the main differential diagnoses for synovial sarcoma in this site. Synovial sarcoma of the digestive tract may be underdiagnosed, and its recognition may have important clinical implications. Fluorescence in situ hybridization is helpful in making this distinction.

A case report of gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation

We report herein an unusual gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation in a 63-year-old Japanese male. The tumor was a pedunculated large polypoid tumor (7 x 6.5 x 3.5 cm) located in the pylorus. Histologically, it invaded to the subserosa and was composed of both adenocarcinomatous and sarcomatous components. Adenocarcinomatous foci generally showed tubular to solid patterns and occupied the parts facing the gastric lumen, while the sarcomatous components showed a generally irregular and solid arrangement. There were transitions between the sarcomatous and carcinoma elements. In addition, carcinoma cells with a cord-like or trabecular arrangement similar to that seen in endocrine carcinoma expressed chromogranin A, and were mainly observed in an intermediate area between the adenocarcinomatous and sarcomatous foci. The sarcomatous areas were mainly composed of spindle cells and occasionally contained a sarcomatous component showing rhabdomyosarcomatous differentiation. This is an interesting case to consider how the variety of cell type appeared in such a type of tumor in the stomach.

Gastric carcinosarcoma (sarcomatoid carcinoma) with rhabdomyoblastic and osteoblastic differentiation

A rare case of carcinosarcoma (sarcomatoid carcinoma) with rhabdomyoblastic and osteoblastic differentiation occurring in the gastric remnant is reported. A 69-year-old Japanese man who had undergone a partial gastrectomy for a duodenal ulcer 30 years earlier, presented with anemia, epigastralgia, and an abdominal mass. The diagnosis of gastric carcinosarcoma was made based on the findings of endoscopic biopsies. The patient was thus scheduled to undergo a surgical operation, but he died of respiratory failure. At autopsy, a huge polypoid tumor measuring 20 x 18 x 8 cm was located on the greater curvature of the gastric remnant. Microscopically, the tumor consisted of intimately mixed tubular adenocarcinoma and heterologous mesenchymal elements containing rhabdomyosarcoma and osteosarcoma. Between these components, a morphological transition from the adenocarcinoma element to the sarcomatous element was observed. Ultrastructually, rhabdomyoblastic differentiation was confirmed in the sarcomatous areas. Immunocytochemical expressions of epithelial markers including epithelial membrane antigen and cytokeratins (35bH11 and 34bE12) were recognized not only in the carcinomatous cells but also in the sarcomatous cells. These findings suggest that carcinomatous cells appear to transform into cells with sarcomatous features.

Sarcomatoid carcinoma of the ampulla of Vater

Sarcomatoid carcinomas (carcinosarcomas) are rare lesions in the gastrointestinal tract, where they are most commonly found in the esophagus. We present the first reported case of a sarcomatoid carcinoma of the ampulla of Vater. The tumor was composed of intermixed carcinomatous (adenocarcinoma plus squamous cell carcinoma) and sarcomatous elements. Cytokeratin immunoreactivity was demonstrated focally in the sarcomatoid component, although in other areas there was positive staining for desmin and smooth muscle actin. The possible histogenesis of such lesions is briefly discussed.

Gastric stump carcinosarcoma with rhabdomyosarcomatous differentiation

Gastric carcinosarcoma is an unusual tumor and its occurrence in the gastric stump is extremely rare. A report is presented here of a unique case of gastric stump carcinosarcoma with rhabdomyosarcomatous differentiation in a 74-year-old man. The patient had undergone partial gastrectomy with gastrojejunostomy (Billroth II method) 30 years previously. The tumor had both adenocarcinoma and sarcoma components, and an immunohistochemical study suggested a focal transition between these components. The main sarcomatous components showed fibrosarcomatous features with a scattered distribution of rounded tumor cells, whose rhabdomyosarcomatous differentiation was immunohistochemically determined. Ultrastructural examination supported the rhabdomyosarcomatous natures. Experience with the present tumor indicates that carcinosarcoma with rhabdomyosarcomatous differentiation can occur in the gastric stump and that this disease is capable of aggressive behavior.

Monoclonal origins of malignant mixed tumors (carcinosarcomas). Evidence for a divergent histogenesis

Malignant mixed tumors (carcinosarcomas) are examples of unusual neoplasms whose occurrences have been observed in increasingly diverse sites but whose pathogenesis remains a complete mystery. Two antithetical hypotheses that have been advanced to explain the histogenesis of these tumors include the convergence hypothesis, which proposes an origin from two or more stem cells (multiclonal hypothesis), and the divergence hypothesis, which proposes an origin from a single totipotential stem cell that differentiates into separate epithelial and mesenchymal directions (monoclonal hypothesis). To test these hypotheses, a novel strategy for the determination of clonality from as few as 100 tumor cells obtained by enzymatic digestion of either fresh or formalin-fixed, paraffin-embedded tissues and cell sorting was used that exhibited the polymerase chain reaction (PCR) in amplifying a 511-bp region located within the first intron of the human hypoxanthine phosphoribosyl transferase gene, a site that contains inactive X chromosomal obligately methylated HpaII/MspI sites and single-base allelic polymorphisms in 5% females. Carcinoma cells gated on the basis of fluorescein isothiocyanate (FITC)-anti-cytokeratin and sarcoma cells gated on the basis of FITC-antivimentin or FITC-anti-desmin were sorted to homogeneity on FACSTAR and then subjected to genomic DNA extraction and Hpa II digestion before PCR amplification and subsequent analysis of the product on denaturing gradient gel electrophoresis. The comigrations of the single homoduplexes generated from both the carcinoma cells and sarcoma cells in six different malignant mixed tumors obtained from four different organs indicated clonal identity and monoclonality in all cases. These findings of monoclonality were confirmed independently by two other methods of clonality determination. The findings of a monoclonal origin of carcinosarcomas support the single totipotential stem-cell-divergence hypothesis.

Gastric adenocarcinoma with differentiation to sarcomatous components associated with monoclonal Epstein-Barr virus infection and LMP-1 expression

A case of gastric adenocarcinoma with sarcomatous differentiation in a 65-year-old male was investigated for possible association with the Epstein-Barr virus (EBV). The presence of EBV-DNA could be proven by the polymerase chain reaction (PCR), and EBERs signals were detected in tumour nuclei, strongly in sarcomatous areas and weakly elsewhere. Monoclonal EBV infection was evident in terms of a single band of lymphocyte determined membrane antigen demonstrated by the PCR method. Latent membrane protein 1 was strongly positive in cells of sarcomatous components but very weakly positive in carcinoma components. EBV-determined nuclear antigen-2 was absent in both. This case of adenocarcinoma suggests that EBV plays an important role in tumorigenesis, contributing in particular to sarcomatous differentiation.

Carcinosarcoma of the stomach. A case report with light microscopic, immunohistochemical, and electron microscopic study

A carcinosarcoma of the stomach in a 66-year-old man is reported. The tumor which had a diameter of 4 cm was an ulcerofungating mass in the posterior wall of the antrum. Histologically it was composed of well-differentiated adenocarcinoma admixed with sarcomatous elements which showed chondrocytic differentiation on light and electron microscopy. The sarcomatous areas were multifocally scattered in the central portion of the tumor and intimately blended with adenocarcinoma cells. CEA immunoreactivity was found not only in the adenocarcinoma but also in the transitional sarcomatous cells, supporting the hypothesis that this tumor might derive from mesenchymal metaplasia of a primarily epithelial neoplasm.