Adenosquamous carcinoma of the gallbladder with spindle cell features. A light microscopic and immunocytochemical study of a case

Synchronous gallbladder squamous cell carcinoma and adenocarcinoma, both as primary tumors in one patient

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We report a male patient with synchronous gallbladder carcinomas.

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This rare condition should be considered in the differential diagnosis of cholecystitis.

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The precise diagnosis of synchronous gallbladder carcinomas by surgeons can lead to proper management and choosing the best surgical strategy.

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It was very interesting that different type of carcinomas affect the gallbladder simultaneously.

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Although synchronous gallbladder carcinomas are very rare, presentation can mimic cholecystitis.

Introduction

Synchronous primary carcinomas of gallbladder are extremely rare. In this paper, we report a case of double primary carcinomas in gallbladder

Case report

A 65 year old male was admitted to the hospital for surgical removal of gallbladder, which was diagnosed as cholecystitis in ultrasonography. Macroscopic examination disclosed a single whitish mass in gallbladder neck and another distinct mass in the fundus as wall thickening. Pathologic findings revealed squamous cell carcinoma of the neck and adenocarcinoma in the fundus.

Discussion

This study represents an example of misdiagnosis. Being cautious is mandatory in order to manage the patient properly.

Conclusion

Synchronous primary carcinomas of gallbladder are rare. However this diagnosis should be taken into account in patients with cholecystitis features in order to seeking for the best surgical approach.

Precancerous lesions of the biliary tree

The neoplasms of the biliary tree include the carcinomas of the intra- and extrahepatic bile ducts, the gallbladder and the ampulla. Two types of precancerous lesions precede these adenocarcinomas: the flat and non-tumour forming type that is called biliary intraepithelial neoplasia, and the papillary and tumour-forming type that has been named intraductal papillary neoplasm of the bile duct. Rarely also biliary mucinous cystic neoplasm can give rise to invasive biliary adenocarcinomas. This review discusses the pathological, molecular, epidemiological, clinical and prognostic features of the precancerous biliary lesions, separated according to their origin in the bile ducts, the ampulla and the gall bladder.

Surgical outcome of carcinosarcoma of the gall bladder: A review

Carcinosarcoma, which comprises less than one percent of all gall bladder neoplasms, is characterized by the presence of variable proportions of carcinomatous and sarcomatous elements. Recently, several reports have described patients suffering from carcinosarcoma of the gall bladder. However, there are no large studies regarding the clinicopathologic features, therapeutic management, and surgical outcome of this disease because the number of patients who undergo resection of gall bladder carcinosarcoma at a single institution is limited. A Medline search was performed using the keywords ‘gall bladder’ and ‘carcinosarcoma’. Additional articles were obtained from references within the papers identified by the Medline search. Optimal adjuvant chemotherapy and/or radiotherapy protocols for carcinosarcoma of the gall bladder have not been established. Curative surgical resection offers the only chance for long-term survival from this disease. The outcome of 36 patients who underwent surgical resection for carcinosarcoma of the gall bladder was poor; the 3-year overall survival rate was only 31.0% and the median survival time was 7.0 mo. Since the postoperative prognosis of carcinosarcoma of the gall bladder is worse than that of adenocarcinoma, new adjuvant chemotherapies and/or radiation techniques are essential for improvement of surgical outcome.

Primary gallbladder sarcoma: a clinicopathologic study of 15 cases, heterogeneous sarcomas with poor outcome, except pediatric botryoid rhabdomyosarcoma

BACKGROUND

Primary gallbladder sarcoma (PGBS) is rare, with only 39 documented cases, with the predominant type being leiomyosarcoma.

DESIGN

Cases recorded as "gallbladder sarcoma" were retrieved from our files; the clinicopathologic features were reviewed and recorded. Only primary gallbladder wall mesenchymal tumors were included. Epithelial tumors, mixed tumors (carcinosarcoma or sarcomatoid carcinoma), tumors extending into the gallbladder from the abdomen, or sarcoma with other known primaries were excluded.

RESULT

PGBS occurred in 4 males and 11 females with the adult median age of 68.5 (range: 24 to 88 y, n=12) and 3 children ages 1.5 to 3 years, the latter all with botryoid embryonal rhabdomyosarcoma. Patients presented with acute and/or chronic cholecystitis, abdominal pain, weight loss, pruritus, elevated alkaline phosphatase and bilirubin, and leukocytosis. The median tumor size was 4.5 cm, mean tumor size 5.7 cm, and range 2.0 to 14.0 cm. Most PGBS involved the entire wall and ulcerated the mucosa. PGBSs were diagnosed as 7 myxofibrosarcomas [malignant fibrous histiocytoma, storiform pleomorphic to myxoid, 2 with an unusual fibromyxoid sarcoma-like (Evans-like), and pleomorphic hyalinizing angiectatic tumor-like mixture], 2 leiomyosarcomas, 1 gastrointestinal stromal tumor-like (GIST-like), 3 botryoid embryonal rhabdomyosarcomas (RMS), and 2 epithelioid angiosarcomas. Diagnosis was based on morphology and immunohistochemistry. A diagnosis of LMS required myoid-intersecting fascicles and diffuse, strong immunoreactivity for smooth muscle actin +/- desmin. RMS revealed myxoid grape-like hypocellular tumor with stellate cells, mild atypia, mitoses and desmin, and myoregulatory protein (MyoD1) and skeletal muscle-specific myogenin (Myf4) reactivity. The GIST-like sarcoma was palisaded and myoid-like but failed to stain for CD34 or CD117. Angiosarcomas demonstrated an extravascular proliferation of atypical epithelioid endothelial cells, and mitotic activity. All cases were negative for S100 protein, HMB45, keratins, and CK18. All patients received cholecystectomy and 6 known adjuvant therapy. Follow-up of 12 revealed that 7 patients died of disease within 3 weeks to 1 year and 4 months after diagnosis, 3 died of unknown causes, and 2, both adjuvant therapy treated botryoid RMS in young children, were alive without disease 11 and 27 years later.

CONCLUSIONS

PGBSs are rare. Carcinosarcoma, spindle cell carcinoma (by use of keratins and CK18), and melanoma must first be excluded. A variety of sarcoma types are found, yet malignant fibrous histiocytoma is the predominant variant, more common than LMS. GIST is a controversial sarcoma in gallbladder; angiosarcoma can rarely occur in this location. PGBS mainly occur in older female adults and have overall poor prognosis. A subgroup of adjuvant therapy-treated botryoid embryonal RMS in the gallbladder of young children, although rare, can have excellent prognosis.

Gallbladder sarcoma: a clinicopathological study of seven cases from the UK and Austria with emphasis on morphological subtypes

BACKGROUND

Primary sarcoma of the gallbladder (PGBS) is rare, with only 40 cases reported in the literature. Most of these have been diagnosed as leiomyosarcoma. We aimed to evaluate the histological features of a case series of this rare tumor and correlate these with clinical features.

DESIGN

Cases recorded as "gallbladder sarcoma" from different institutes were reviewed and the clinicopathological features of these cases were recorded. Only primary gallbladder wall mesenchymal tumors were included. Epithelial tumors, mixed tumors (carcinosarcoma or sarcomatoid carcinoma), and tumors extending into the gallbladder from the abdomen or sarcoma with other known primaries were specifically excluded.

RESULT

PGBS occurred in one male and six females with a median age of 70 (range 64-82) years. Patients presented with acute or chronic cholecystitis, abdominal pain, weight loss, and pruritus. They were generally found to have elevated alkaline phosphatase and bilirubin, and leukocytosis. Tumors ranged from 1.1 to 4 cm with a median size of 3 cm. Most PGBS arose in the body but one arose in the fundus. All tumors were associated with ulcerated mucosa. Based on morphological and immunohistochemical features of the PGBS, there were three myxofibrosarcomas (malignant fibrous histiocytoma, MFH, storiform pleomorphic), one leiomyosarcoma (LMS), one angiosarcoma (AS), and two liposarcomas (LS). All patients received cholecystectomy and three received adjuvant chemotherapy. Follow-up revealed that six patients died of the disease 6 weeks to 2 years after diagnosis and one died of unrelated causes.

CONCLUSION

PGBS are rare and mainly occur in the gallbladder body in middle-aged females. They generally present with acute cholecystitis and have a very poor prognosis. A variety of sarcoma types are found with MFH being the predominant variant.

Adenosquamous/squamous cell carcinoma of the gallbladder

BACKGROUND AND OBJECTIVES

Adenosquamous/squamous cell carcinoma is a rare histopathologic subtype of gallbladder malignancy. Its clinical features have rarely been described, and its differences from the major histopathologic subtype, adenocarcinoma, remain uncertain.

METHODS

All patients with gallbladder carcinoma were retrospectively reviewed. Patients with a histopathologic subtype of either adenosquamous (n = 12) or squamous cell (n = 2) carcinoma were categorized to group I, and patients with adenocarcinoma were categorized to group II. The clinical characteristics and outcomes of these two groups were compared.

RESULTS

The two groups were generally no different in clinical features. However, tumor stages of group I patients were significantly advanced (P = 0.048) and included liver involvement (P = 0.008). The outcomes of advanced-stage patients in group II were not different from group I (P = 0.413). Nevertheless, patients in both groups with advanced stage pT who had undergone curative resection showed significantly better survival curves than patients who had undergone non-curative resection (P = 0.003).

CONCLUSIONS

Patients with adenosquamous/squamous cell carcinoma of the gallbladder were generally similar to those with adenocarcinoma in clinical characteristics, but had a tendency for liver infiltration. Although the two histopathologic subtypes of the gallbladder carcinoma had similar poor outcomes, better survival could be obtained by performing curative resection for these patients.

Primary undifferentiated spindle-cell carcinoma of the gallbladder presenting as a liver tumor

Undifferentiated spindle-cell carcinoma (SpCC) of the gallbladder is extremely rare. There is very little information available regarding the characteristics and treatment of this disease. We herein report the unique case of a 76-year-old female patient with a primary SpCC of the gallbladder that presented as a liver tumor. Preoperative radiologic examinations showed a 5-cm liver tumor around the gallbladder bed, and irregular thickening of the gallbladder wall. The patient underwent en-bloc resection of the gallbladder and segments 4b and 5 of the liver (including the liver tumor). Microscopic findings revealed that both lesions consisted mainly of a sarcomatous spindle-shaped component. Small foci of well-differentiated adenocarcinoma cells were identified in the gallbladder mucosa. There was a gradual transition between the two different components, thereby implying that these two cell types had a common origin. Immunohistochemical studies showed that the spindle-shaped cells were epithelial in nature. The patient's postoperative course was uneventful. However, she died of recurrent liver disease 6 months after the surgery. In conclusion, we surmised that the sarcomatous spindle cells originated from a carcinomatous component in the gallbladder mucosa through dedifferentiation. Further studies are needed to better understand the characteristics of this deadly tumor, and to establish an effective therapy for it.

Sarcomatoid carcinoma with components of small cell carcinoma and undifferentiated carcinoma of the gallbladder

We report a case of sarcomatoid carcinoma with components of small cell carcinoma and undifferentiated carcinoma of the gallbladder. An 84-year-old woman was admitted to our university hospital with right upper abdominal pain and back pain. Clinical diagnosis of a gallbladder tumor was made based on the findings of abdominal ultrasonography, computed tomography and endoscopic retrograde cholangiopancreatography, and a cholecystectomy was carried out. On gross examination a pedunculated polypoid tumor protruded into the lumen of the gallbladder. Histologically the tumor was composed of carcinomatous and sarcomatous components; the carcinomatous component consisted mainly of small cell carcinoma and undifferentiated carcinoma. In general, the carcinomatous component of sarcomatoid carcinoma of the gallbladder consists of adenocarcinoma, and there have only been two previously reported cases in which the carcinomatous component consisted of small cell carcinoma or undifferentiated carcinoma. Because the patient's prognosis may be influenced by the peculiar carcinomatous component in such cases, it is important to accumulate case reports that clarify their clinicopathological features.

Polypoid leiomyosarcoma of the gallbladder: Study of a case associated with adenomyomatous hyperplasia

A case of polypoid leiomyosarcoma of the gallbladder arising in association with pre-existing adenomyomatous hyperplasia is described. The patient, a 34-year-old woman with symptoms of cholelithiasis, underwent a cholecystectomy for gallstones. The resected specimen showed, in addition to multiple stones, a large, rubbery, broad-based polypoid mass in the fundus. Histologic examination showed a malignant spindle cell proliferation with immunophenotypic features of smooth muscle differentiation. The base of the lesion showed features of adenomyomatous hyperplasia. The possible relationships of this lesion with adenomyomatous hyperplasia and other stromal lesions of the gallbladder are reviewed.

Adenosquamous carcinoma of the small intestine. Report of a case and review of the literature

Primary adenosquamous carcinomas of the intestine are rare tumors, particularly those occurring in the small bowel. We report the third case of an adenosquamous carcinoma of the ileum in a 55-year-old-man. Histologically, the tumor consisted of malignant glandular and squamous elements. A review of the literature is presented.

Fine-needle aspiration of primary gallbladder carcinoma

Primary carcinoma of the gallbladder is a rare neoplasm that is frequently difficult to diagnose preoperatively. The obstacles to diagnosis include vague symptoms and the relative inaccessibility of the gallbladder and cystic duct to biopsy. Cytological descriptions of gallbladder carcinoma are sparse and are largely confined to malignant cells identified in aspirated bile. Examination of bile is a fairly insensitive technique for diagnosing carcinoma, partially due to the degradative effect of biliary salts on cellular morphology. In the following, we report the findings of three cases of primary carcinoma of the gallbladder examined by fine-needle aspiration cytology.

Spindle cell hepatocellular carcinoma. A clinicopathologic and immunohistochemical analysis of 15 cases

BACKGROUND

Spindle cell hepatocellular carcinoma (SpHCC) has rarely been reported, and its clinicopathologic characteristics, histogenesis, and prognosis after hepatic resection have yet to be clarified.

METHODS

Fifteen cases of SpHCC, including 13 surgically resected patients and 2 autopsy cases, were studied clinicopathologically and immunohistochemically.

RESULTS

In 13 resected patients, all except 1 were male and the serum alpha-fetoprotein (AFP) was positive in 6 (46%). Portal venous invasion and intrahepatic metastases were frequent. In an immunohistochemical analysis of 13 SpHCC tumors, cytokeratin CAM 5.2 and AFP were positive in 8 (62%) tumors and 3 (23%) tumors in both ordinary HCC and spindle cell components, respectively. The spindle cell components, but not ordinary HCC components, revealed a positive reaction for vimentin in 8 (62%) tumors, S-100 protein and HAM-56 in 3 (23%) tumors, HHF-35 in 2 (15%) tumors, and alpha-smooth muscle actin, desmin, and KP-1 in 1 (8%) tumor, respectively. p53 overexpression was found in two SpHCC tumors. The survival curve after hepatic resection in the 13 patients with SpHCC was significantly worse than that of the 371 patients with Stage II-IV ordinary HCC (P < 0.001).

CONCLUSIONS

These results suggest that SpHCC represents a sarcomatous transformation of HCC. The spindle cell components revealed an immunohistochemical expression of several markers of mesenchymal cells. In addition, poor survival after hepatic resection was documented.

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 spindle cell sarcomatous change of hepatic ducts manifesting as obstructive jaundice

Spindle cell carcinoma is a rare tumor commonly occurring in the upper aerodigestive tract. We report a 62-year-old male with spindle cell sarcomatous change located at the hepatic hilum, resulting in obstructive jaundice. The patient died after an extended resective operation. The rare disease and its histogenesis is discussed.

Adenosquamous carcinoma of the gall-bladder with gastric foveolar-type epithelium

An 80 year old Japanese man had adenosquamous carcinoma of the gall-bladder characterized by an adenocarcinoma (AC) in the gall-bladder lumen and a squamous cell carcinoma (SCC) in the invaded region of the liver. In the AC, the tumor cells consisted of atypical columnar epithelium with pseudostratification, mimicking gastric foveolar epithelium, while atypical signet-ring cells were scattered within the SCC. There was an abrupt transition between the AC and SCC areas. The tumor cells in the AC area were intensely positive for galactose oxidase-Schiff staining, and paradoxical concanavalin A staining revealed these tumor cells to have Class II mucins. Immunohistochemically, the tumor cells in foveolar-type adenocarcinoma were diffusely positive for cathepsin D. Flow cytometrical analysis of DNA content showed the AC area to be diploid and the SCC area to be aneuploid. The S-phase fraction of the SCC area (46.9%) was larger than that of the AC area (19.5%). The positive rate of immunostaining for proliferating cell nuclear antigen in the SCC area (mean 50.627%) was larger than that of the AC area (mean 3.048%, P < 0.01). These results suggest that the AC area of this tumor, histochemically and immunohistochemically, showed gastric foveolar-type characteristics, the SCC component was squamous cell metaplasia of the pre-existing AC, and that the SCC area had a greater proliferating capacity than the AC area.

Liver, gallbladder, extrahepatic bile ducts, and pancreas

BACKGROUND

The liver, gallbladder, bile ducts, and pancreas have a common embryologic origin; cancers that arise from these sites therefore are expected to share a similar spectrum of histologic types. These cancers are known for their extremely poor prognoses.

METHODS

Data from the Surveillance, Epidemiology, and End Results Program regarding the incidence, distribution of histologic types, stage of disease, and survival for cancers of the gallbladder (n = 4412), extrahepatic bile ducts (n = 3486), pancreas (n = 23,116), and liver (n = 6,391) were reviewed. The most common histologic types are discussed, and the frequency of rare types is reported.

RESULTS

The incidence of biliary cancer decreased, while the incidence of hepatic and pancreatic cancer rose slightly over the 15-year period from 1973 to 1987. Age and sex distributions varied by histologic type. Greater than 98% of pancreatic and biliary cancers were carcinomas, and adenocarcinoma (not otherwise specified) was the most common histologic type recorded. In the liver, hepatocellular carcinoma was the most common type, followed by intrahepatic cholangiocarcinoma. The overall 5-year relative survival rates for these cancers were very low: gallbladder, 12.3%; extrahepatic bile duct, 12.7%; liver 3.1%; and pancreas 2.5% (all stages combined, 1978-1986).

CONCLUSIONS

This review confirmed that these carcinomas are associated with a very poor outcome; however, survival was influenced by stage of disease and histologic type. In the gallbladder and extrahepatic bile ducts, papillary adenocarcinoma was associated with the best outcome of all histologic types, and in the exocrine pancreas, mucinous cystadenocarcinoma was associated with the best prognosis.

Adenosquamous carcinoma of the gallbladder: a clinicopathological, immunohistochemical and flow-cytometric study of twenty cases

Twenty patients (7.4%) with adenosquamous carcinoma of the gallbladder were selected from 271 surgically resected gallbladder cancers. The 20 patients were composed of 8 men and 12 women with a mean age of 66.9 years. Histologically, all twenty tumors showed an abrupt transition between the adenocarcinoma (AC) and squamous cell carcinoma (SCC) areas, and well differentiated AC was also found in the peripheral area of the tumor. A histochemical and immunohistochemical study using alcian blue, periodic acid-Schiff, cytokeratins, involculin and tissue polypeptide antigen disclosed a different nature of the two components. DNA heterogeneity between the components was detected in 5 of 7 cases by flow cytometry. The positive rate of immunostaining for proliferating cell nuclear antigen in the SCC areas (mean 20.55%) was larger than that of the AC areas (mean 11.40%) (P = 0.0029), which indicated that the SCC areas had a greater proliferative capacity than AC areas. These results suggest that the SCC component of adenosquamous carcinoma of the gallbladder arose by a stepwise molecular progression of the pre-existing AC. Furthermore, the prognosis of adenosquamous carcinomas of the gallbladder (mean survival: 10 months) in the advanced stage (pTNM 2-4) was less favorable than those of papillary and well differentiated AC (mean survival: 99 months and 86 months) (P < 0.0001).

Undifferentiated spindle cell carcinoma of the gallbladder: a clinicopathologic, immunohistochemical, and flow cytometric study of 11 cases

Eleven primary spindle cell carcinomas (SpCCs) of the gallbladder are reported. They occurred in eight women and three men ranging in age from 59 to 80 years (mean age, 66.5 years). Histologically, the tumors showed interlacing bundles of atypical spindle cells with eosinophilic cytoplasm, oval to elongated nuclei, and conspicuous nucleoli. Eight SpCCs contained tiny foci of neoplastic glands similar to those seen in adenocarcinoma, and two of these cases also had small foci of neoplastic squamous epithelium. A gradual transition between the squamous cell carcinoma and the spindle cell component was observed in one tumor. Immunohistochemically, all SpCCs were positive for at least one of the epithelial markers (epithelial membrane antigen, nine cases; AE1/AE3, nine cases; carcinoembryonic antigen, three cases; and EAB 903, one case), and the tumor cells also were immunoreactive to mesenchymal marker (vimentin, eight cases), muscle markers (alpha-smooth muscle actin, one case; desmin, one case), and histiocytic marker (HAM 56, one case). Abnormalities in tumor suppressor gene p53 expression also were found in two of the 11 SpCC cases using monoclonal antibody PAb 1801. In six cases for which data were available flow cytometry revealed aneuploidy in three SpCCs (50%). The survival curve of the SpCC cases (mean survival, 9 months) was less favorable than that of 224 cases of adenocarcinoma of the gallbladder (mean survival, 81 months) (P = .0011). These results indicate that SpCC of the gallbladder is an epithelial tumor with sarcomatoid components and its prognosis is unfavorable.

Carcinosarcoma in Barrett's oesophagus: a case report with immunohistological examination

A case of a carcinosarcoma which developed in a Barrett's oesophagus is presented. The tumour consisted of an adenocarcinoma and a spindle cell sarcoma. Immunohistological examinations demonstrated vimentin positivity in the sarcomatous portion with a negative reaction for keratin. Immunohistological and histological findings did not rule out the possibility of a double or collision tumour in this case.

Pseudoangiosarcomatous carcinoma: a clinicopathological study of seven cases

Seven cases of carcinoma mimicking angiosarcoma occurring in skin (3 cases), breast (3) and lung (1) are described. The cutaneous, pulmonary and one of the breast carcinomas were poorly differentiated and squamous in type; the other two breast tumours were poorly differentiated ductal carcinomas with focal squamous differentiation. Histologically, the pseudoangiosarcomatous pattern was due to complex anastomosing channels and spaces lined by neoplastic cells. The spaces contained hyaluronic acid. The neoplastic cells exhibited cytokeratin positivity but yielded negative results with the endothelial cell markers, factor VIII-related antigen and CD 34 (QB-END/10). Two breast tumours showed binding of UEA-1. Ultrastructurally, unequivocal epithelial differentiation was demonstrated in six of the cases. Pathogenetically, these tumours appeared to be variants of acantholytic squamous cell carcinoma. Recognition of this unusual form of carcinoma is important, as an incorrect diagnosis of angiosarcoma may lead to inappropriate treatment and prognostication.

Tubular adenoma of the gallbladder with squamoid spindle cell metaplasia. Report of three cases with immunohistochemical study

Three cases of tubular adenoma of the gallbladder with squamoid spindle cell metaplasia are reported. Two of the three patients, who were middle-aged Japanese, had a solitary polyp in the gallbladder, and the other had three polyps. All the lesions were detected incidentally by ultrasonography. The polyps were pedunculated with a fine or frail stalk, and ranged from 0.5 to 3.9 cm in diameter. Histologically, they were tubular adenomas accompanied by scattered foci composed of a compact collection of short-spindle or oval cells with mild atypia. These cells did not retain intercellular bridges, and lacked intracellular keratinization. Immunohistochemically, the spindle cells stained positively for high-molecular-weight cytokeratin (EAB 903, a marker of squamous cell differentiation), whereas adenoma cells lining the tubules were negative for this antigen. Therefore, the spindle cell component is considered to represent squamoid metaplasia of adenoma cells.

Undifferentiated carcinoma of the gallbladder. A clinicopathologic, histochemical, and immunohistochemical study of 21 patients with a poor prognosis

Among 284 cases of carcinoma of the gallbladder, 21 were identified as undifferentiated carcinoma (UC), with little glandular or other specific epithelial differentiation. These tumors were classified into three histologic types according to the components: (1) small cell type (eight cases); (2) pleomorphic cell type (eight cases); and (3) spindle cell or pseudosarcomatous type (five cases). Histochemical and immunohistochemical study by the immunoperoxidase technique revealed that most of the tumors (13/21) contained mucosubstances, and that all examples of the UC were immunoreactive for epithelial membrane antigen (EMA), keratin, and carcinoembryonic antigen (CEA), thereby indicating the epithelial nature of the neoplastic cells. Vimentin immunoreactivity was found in nine tumors. In 19, the tumor contained various neoplastic endocrine cells, including somatostatin-immunoreactive (14/19), gastrin-immunoreactive (14/19), human chorionic gonadotropin (HCG)-immunoreactive (9/19), pancreatic polypeptide-immunoreactive (4/19), and serotonin-immunoreactive cells (4/19). The prognosis of patients with UC of the gallbladder was poorer than that of patients with differentiated adenocarcinoma.