Gastric hamartomatous inverted polyp: Report of three cases with a review of the endoscopic and clinicopathological features.

Objectives: A gastric hamartomatous inverted polyp (GHIP) is a rare submucosal tumor characterized histopathologically by a submucosal inverted proliferation of cystically dilated hyperplastic gastric glands. Only 42 GHIPs have been reported in English literature. Few GHIPs have been reported to accompany adenocarcinomas. We reported on three patients with a GHIP and reviewed the clinicopathological and endoscopic features of GHIPs. Methods: This study included two men and one woman with a GHIP. The endoscopic, histopathological, and immunohistochemical features of the endoscopically resected specimens were analyzed. A gene mutation analysis was also performed. Results: All the tumors were located in the body of the stomach, with a median size of 20 mm. Two tumors were sessile, and the remaining tumor had a pedunculated appearance. The overlying mucosa mainly appeared normal but was reddish in one tumor. The histopathological examination of the tumors revealed a well-circumscribed and lobular submucosal proliferation of cystically dilated hyperplastic glands. The immunohistochemical analysis revealed that the MUC5AC-positive foveolar epithelium was located in the center, and MUC6-positive pseudo-pyloric or pepsinogen-I and H+/K+ ATPase-positive fundic-type glands were located at the periphery of two tumors. No carcinomatous components were noted in any of the tumors. Moreover, no significant mutations in oncogenes or tumor suppressor genes were noted. Conclusions: Our review revealed that approximately three fourths of GHIP cases showed an submucosal tumor-like feature, whereas endoscopic features, including the endoscopic ultrasonography findings, were not characteristic. Because an endoscopic diagnosis of a GHIP may be difficult, complete endoscopic resection may be required for a pathological diagnosis.

[A Case of Retroperitoneal Bronchogenic Cyst Diagnosed by Fluorescence in situ Hybridization].

A 50-year-old woman was referred to our hospital for consultation for a suspected left adrenal tumor detected by ultrasonography during a health check. Computed tomography and magnetic resonance imaging revealed a 4.7×3.4 cm tumor in the retroperitoneal space near the adrenal gland. The patient subsequently underwent laparoscopic tumor resection. Using fluorescence in situ hybridization (FISH), the resected tumor was diagnosed as a retroperitoneal bronchial cyst. Here we present a case of a definitive diagnosis of a retroperitoneal bronchial cyst using FISH, and review the cases of retroperitoneal bronchial cyst in the literature.

Fine-needle aspiration cytology of Warthin-like mucoepidermoid carcinoma: A case report with cytological review.

Warthin-like mucoepidermoid carcinoma (MEC) is a novel and rare subtype of MEC and is characterized histopathologically by the presence of abundant lymphocytic infiltration and cystic changes. A small number of cytological reports of this MEC variant is currently available. The present study reported on the sixth cytological case of Warthin-like MEC, reviewed the cytological features of the tumour and discussed the cytological differential diagnosis. A 16-year-old Japanese female presented with a painful mass in the left parotid gland. Fine-needle aspiration for cytological examination of the parotid gland tumour was performed, followed by partial parotidectomy. Cytological examination revealed sheet-like and folded epithelial cell clusters in a mucinous background accompanying abundant lymphocytic infiltration. Epithelial clusters comprised round cells with mildly enlarged round to oval nuclei, polygonal cells with relatively rich cytoplasm and slightly enlarged round to oval nuclei. Certain polygonal cells contained intracytoplasmic mucin. Histopathological examination of the resected parotid gland tumour indicated multiple cystic lesions with abundant lymphocytic infiltration accompanying lymphoid follicle formation. The cysts were lined by intermediate cells with occasional mucinous cells. Fluorescence in situ hybridization using the surgically resected specimen indicated mastermind-like transcriptional coactivator 2 (MAML2) rearrangement, a characteristic of Warthin-like MEC. Consequently, the patient was diagnosed with Warthin-like MEC. The literature review revealed that the characteristic cytological features of Warthin-like MEC are the presence of intermediate cells and lack of oncocytic cells in the mucinous material under an abundant lymphocytic background. Clinicopathological features may help with a differential diagnosis, particularly from Warthin's tumour, and detection of MAML2 rearrangement is able to improve the accuracy of diagnosis.

Utility of an immunocytochemical analysis for pan-Trk in the cytodiagnosis of secretory carcinoma of the salivary gland.

Secretory carcinoma (SC) of the salivary gland is a rare distinct clinicopathological entity characterized by the presence of the ETV6-NTRK3 fusion. Although the characteristic cytological features of SC have been recognized, its cytodiagnosis, especially differentiating SC from acinic cell carcinoma, is challenging. Recent studies have revealed that immunohistochemistry for pan-tyrosine receptor kinase (Trk) and nuclear receptor subfamily 4 group member 3 (NR4A3) are specific for SC and acinic cell carcinoma, respectively. However, the usefulness of immunocytochemical detection of these markers in the diagnosis of SC has not been addressed. Hence, the present study aimed to analyze the usefulness of immunocytochemical staining for pan-Trk and NR4A3 in the cytodiagnosis of SC. We enrolled eight patients with a histopathological diagnosis of SC who underwent preoperative fine-needle aspiration cytological examination. The cytological characteristics were reviewed and immunocytochemical staining for pan-Trk and NR4A3 was performed. The characteristic cytological features noted in the patient cohort included neoplastic cell clusters with a sheet-like and papillary cluster arrangement as well as single cells. Additionally, neoplastic cells with mild to moderately enlarged nuclei and small nucleoli, multi-vacuolated cytoplasm, and intracytoplasmic mucin were also observed. The immunocytochemical analyses clearly demonstrated that all eight specimens showed positive nuclear staining for pan-Trk, but were negative for NR4A3 expression. Although all cases of SC do not always show positive immunoreactivity for pan-Trk, immunocytochemical analysis for pan-Trk may be useful for the cytodiagnosis of SC along with assessment of the characteristic cytological features.

Emergent salvage surgery for massive hemoptysis after proton beam therapy for lung cancer: a case report.

BACKGROUND: Salvage surgery is an effective therapeutic option for patients experiencing relapses after chemoradiotherapy for advanced-stage lung cancer or after high-dose radiotherapy for early-stage lung cancer. We report a case involving an emergent salvage surgery for a patient with massive hemoptysis who developed lung cancer recurrence after undergoing proton beam therapy 7 years prior to presentation. CASE PRESENTATION: A 70-year-old male patient was emergently admitted due to massive hemoptysis. He had undergone proton beam therapy for a stage I adenocarcinoma of the left upper lobe 7 years ago, and was receiving chemotherapy for local recurrence. We performed an emergent salvage pulmonary resection to achieve hemostasis. During the operation, we confirmed the presence of a left broncho-pulmonary arterial fistula, which was considered as the origin of the massive hemoptysis. We repaired the fistula between the pulmonary artery and left upper bronchus without incident; an orifice of the fistula at the left pulmonary artery was sutured using a non-absorbable monofilament, and the central portion of the orifice of the fistula at the left upper bronchus was closed with a mechanical stapling device. The postoperative diagnosis was of an adenocarcinoma-ypT3(pm1) N0M1a (dissemination)-IVA, ef1b. The patient has survived for over a year with the cancer in almost complete remission following the administration of an epidermal growth factor receptor tyrosine kinase inhibitor. CONCLUSIONS: Emergent salvage surgery demands high skill levels with optimal timing and correct patient selection. Our case suggested that the procedure played an important role in controlling serious bleeding and/or infectious conditions. Consequently, he could receive chemotherapy again and survive for over a year.

Signet-ring cell/histiocytoid carcinoma in the axilla: A case report with genetic analysis using next-generation sequencing.

Signet-ring cell/histiocytoid carcinoma (SRCHC) is a very rare skin appendage cancer, with an extremely rare occurrence in the axilla. This study describes the 11th case of SRCHC occurring in the axilla and reports the first gene alteration analysis performed for SRCHC. An 85-year-old Japanese male presented with a tumor in the left axilla. Biopsy of the axilla nodule demonstrated diffuse proliferation of histiocytoid neoplastic cells and signet-ring cells in the dermis and subcutis. Immunohistochemistry revealed loss of E-cadherin expression in these neoplastic cells. Accordingly, SRCHC of the axilla was diagnosed. Genetic analysis using next-generation sequencing demonstrated missense mutation of PIK3CA (c1633G>A, pGlu545Lys) and no CDH1 gene mutation.SRCHC of the axilla is considered equivalent to a histiocytoid variant of invasive lobular breast carcinoma. The present SRCHC case demonstrated a pathogenic PIK3CA mutation, which is observed in invasive lobular carcinoma. Additional large case studies are required to clarify the clinicopathological features and gene alterations in SRCHC of the axilla.

Robot-assisted laparoscopic vesicule prostatectomy for mixed epithelial-stromal tumor of seminal vesicle.

INTRODUCTION: Mixed epithelial-stromal tumor is a biphasic tumor with stromal and benign epithelial components. Only 40 cases of mixed epithelial-stromal tumor originating from a seminal vesicle have previously been published in English. CASE PRESENTATION: A 52-year-old man was transferred to our hospital for evaluation of a 3.0-cm pelvic tumor detected incidentally by computed tomography. Robot-assisted laparoscopic vesicle prostatectomy was performed. We approached the Retzius space from both levels of the pouch of Douglas and peritoneal top of the bladder to clarify the tumor's environment. Pathologically, the tumor was diagnosed as a low-grade mixed epithelial-stromal tumor originating from the right seminal vesicle. There was no evidence of disease recurrence within 51 months. CONCLUSION: This is the first report of robot-assisted laparoscopic vesicle prostatectomy for a seminal vesicle mixed epithelial-stromal tumor. Long-term observation is warranted due to the lack of reports with sufficient follow-up to ensure the procedure's safety.

Intramural bronchogenic cysts of the esophagus and gastroesophageal junction: A case report.

Bronchogenic cyst is a relatively rare congenital malformation that is often identified in the mediastinum. The occurrence of bronchogenic cysts in the intramural esophagus and gastroesophageal junction is rare. The present report describes three cases of intramural bronchogenic cysts of the esophagus and gastroesophageal junction and reviews the clinicopathological features of these lesions. A 35-year-old Japanese male (Case 1), a 50-year-old Japanese woman (Case 2) and a 34-year-old Japanese man (Case 3) presented with dysphagia, pharyngeal pain and heartburn, respectively. Upper endoscopic examination revealed submucosal tumors in the esophagus (Case 1 and 2) and gastroesophageal junction (Case 3). Subsequent endoscopic examination revealed perforation of the cyst into the surface of the esophageal mucosa (Case 2). Surgical resection was performed in all cases. Histopathological examinations revealed that the submucosal cysts were covered by respiratory-type ciliated epithelium without atypia. Cartilage and bronchial glands were not observed in any of the cases. The present review of the clinicopathological characteristics of bronchogenic cysts of the esophagus and gastroesophageal junction revealed that males and females were equally affected. The median age of the patients was 34.5 years with a wide age distribution. The most common main complaint was dysphagia. A pre-operative diagnosis of bronchogenic cyst is difficult because no specific imaging features are present. As surgical resection is recommended for this lesion, recognition of the clinicopathological features of bronchogenic cysts is important for an accurate pre-operative diagnosis.

Prominent oncocytic metaplasia in pleomorphic adenoma: A potential diagnostic pitfall.

Pleomorphic adenoma (PA) is the most common salivary gland tumor. The cytological features of PA are well recognized, and its diagnosis is straightforward in most cases. Some metaplastic changes in PA are well known; however, occurrence of oncocytic metaplasia in PA is very rare. In this report, we describe the first cytological case of prominent oncocytic metaplasia in PA identified based on immunocytochemical analysis. We report the case of a 62-year-old Japanese female who presented with swelling of the left neck region. A fine-needle aspiration cytologic examination was performed followed by surgical resection. The Papanicolaou smear revealed the presence of discohesive neoplastic cells in a myxoid background. These neoplastic cells had a relatively rich, granular cytoplasm, and round nuclei with moderate pleomorphism. Initial cytodiagnosis revealed carcinoma ex PA (CXPA). Immunocytochemical analysis showed that abundant mitochondria were present in the cytoplasm of these neoplastic cells. Histopathological examination of the resected tumor demonstrated proliferation of oncocytic neoplastic cells within a myxoid material and the presence of conventional PA components. A final diagnosis of prominent oncocytic metaplasia in PA was made. Oncocytic metaplasia showed nuclear atypia and pleomorphism; therefore, CXPA, which presents with severe nuclear atypia and necrotic background, must be differentiated from oncocytic metaplastic PA. Recognition of oncocytic metaplasia in PA is important for correct diagnosis.

Wagner-Meissner neurilemmoma of the lip occurring in a patient with neurofibromatosis type 1: A case report.

Wagner-Meissner corpuscles are specialized mechanoreceptors located in the dermal papillae. Wagner-Meissner corpuscle-like structures are occasionally a component of certain types of tumors, such as melanocytic nevus and neurofibroma. Benign tumorous lesion entirely composed of Wagner-Meissner corpuscles are described as Wagner-Meissner neurilemmoma, and only four such cases have been reported. Here, we report the first case of Wagner-Meissner neurilemmoma in a patient with neurofibromatosis type 1. A 16-year-old Japanese male with neurofibromatosis type 1 presented with a tumorous lesion on the upper lip. Resection of the tumor was performed under a clinical diagnosis of neurofibroma. Histopathological examination revealed an unencapsulated, poorly-circumscribed tumor, comprised of abundant Wagner-Meissner corpuscle-like structures, which were composed of 5-15 lamellated Schwann cells containing eosinophilic cytoplasm and peripherally located nuclei. No spindle-shaped neoplastic cell proliferation, as seen in conventional neurofibroma, was observed. Accordingly, a diagnosis of Wagner-Meissner neurilemmoma was made. The pathogenesis of Wagner-Meissner neurilemmoma remains unclear. The hamartomatous or reactive proliferative nature has been proposed. In addition, this lesion may represent an extreme form of diffuse neurofibroma with abundant Wagner-Meissner corpuscles associated with neurofibromatosis type 1, even though the previously reported four patients did not have neurofibromatosis. Therefore, further studies are needed to clarify the pathogenesis of this extremely rare tumor, including its association with neurofibromatosis.

Immunohistochemical analyses to determine pathogenesis of tenosynovitis with psammomatous calcification in the wrist: A case report.

Tenosynovitis with psammomatous calcification is an extremely rare clinicopathological condition, which is characterized histopathologically by the presence of numerous psammomatous calcifications surrounded by a granulomatous reaction comprising a mixture of histiocytes and fibroblasts. The pathogenesis of this disease remains unclear, although an association with repetitive tendinous injury has been proposed. The present study describes the details of a case in an elderly Japanese female, and, to the best of our knowledge, the first known immunohistochemical analysis of the mechanism underlying psammomatous calcification formation. A 66-year-old Japanese woman presented with pain in the right wrist. The lesion was surgically resected. Histopathological examination revealed a well-circumscribed lesion composed of psammomatous calcification. The calcification was surrounded by histiocytes, and a few multinucleated giant cells and fibroblastic spindle cells. Immunohistochemical study revealed that these histiocytes were positive for cluster of differentiation 163, and the histiocytes and spindle cells surrounding the psammomatous calcification expressed bone morphogenetic protein-1 (BMP-1). Tenosynovitis with psammomatous calcification is hypothesized to be a distinctive subtype of idiopathic calcifying tenosynovitis involving an unusual reactive or degenerative process. BMP-1 has been demonstrated to be involved in the regulation of hard tissue mineralization, and its expression has been suggested to be associated with psammoma formation in papillary thyroid cancer. To the best of our knowledge, the case report within the present study suggested for the first time that BMP-1 expression was associated with development of psammomatous calcification in this condition.

Simultaneous gastric adenosquamous carcinoma and gastric carcinoma with lymphoid stroma: A case report.

Primary gastric adenosquamous carcinoma (ASC) is a rare tumor, and gastric carcinoma with lymphoid stroma (GCLS) is a distinct and relatively rare tumor, which is characterized histopathologically by prominent lymphoid infiltration and is commonly associated with Epstein-Barr virus (EBV) infection. The association between ASC and GCLS has been poorly understood, and only two cases of concomitant occurrence of ASC and GCLS have been reported previously. In this report, we describe the first documented case of simultaneous gastric ASC and GCLS. A 58-year-old Japanese male complained of loss of appetite. Gastric endoscopic examination revealed a type 3 tumor in the antrum. Distal gastrectomy with lymph node dissection was performed after neoadjuvant chemotherapy. Macroscopic examination of the resected specimen revealed two discontinuous lesions in the antrum. The first lesion, an ASC, was detected preoperatively by endoscopic examination. This type 3 tumor was composed of a mixture of squamous cell carcinoma (~75% of the tumor) and poorly-to-moderately differentiated adenocarcinoma (~25%). No EBV-encoded RNA (EBER)-positive neoplastic cells were noted. The tumor had invaded into the serosa. The second lesion was a GCLS, which was not preoperatively detected by endoscopic examination. The neoplastic cells of the GCLS were EBER-positive. The tumor had invaded into the muscularis propria. Accordingly, a diagnosis of simultaneous gastric ASC (pT4a) and GCLS (pT2) was made. The pathogenesis of gastric ASC has been under debate. Only limited cases of ASC associated with EBV have been reported. Notably, EBV has not been associated with the development of an ASC component in the previously reported concomitant cases of ASC and GCLS, as well as in the present case study. Therefore, additional studies are required to clarify the pathogenesis of gastric ASC, including its association with EBV.

Utility of endoscopic ultrasound-guided fine-needle aspiration cytology in rapid on-site evaluation for the diagnosis of gastric submucosal tumors: Retrospective analysis of a single-center experience.

BACKGROUND: Recently, there have been reports of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology being used for the diagnosis of various kinds of tumors. This method has also been adopted in the diagnosis of gastric submucosal tumors (SMTs). The aim of this study was to analyze the utility of EUS-FNA cytological examination in rapid on-site evaluation (ROSE) for gastric SMTs. METHODS: Retrospective analyses of the cytological specimens of EUS-FNA in ROSE for gastric SMTs and determination of the diagnostic accuracy of EUS-FNA combined with immunohistochemical analysis of cell blocks and surgically resected specimens were performed. RESULTS: A total of 110 patients were enrolled in this study. The most common cytodiagnosis was spindle cell tumor (62 patients, 55.5%), followed by negative for tumor (34 patients), and malignant lymphoma and adenocarcinoma (five patients each). Cell blocks were prepared for 60 of the patients (96.8%), cytologically diagnosed with spindle cell tumor. Immunohistochemical analyses using cell block revealed gastrointestinal stromal tumor (GIST, c-kit+ /desmin- , 49 patients) and leiomyoma (desmin+ /c-kit- , five patients). Thus, using EUS-FNA specimens, 83.1% of GIST patients were pre-operatively diagnosed. CONCLUSIONS: EUS-FNA cytological examination in ROSE for gastric SMTs aided in the collection of sufficient amounts of tumor tissues for preparing cell blocks. This method led to a high rate of accurate pre-operative diagnosis in patients with gastric SMTs.

Hepatectomy in a case of hepatocellular carcinoma with constitutional indocyanine green excretory defect.

INTRODUCTION: Constitutional indocyanine green (ICG) excretory defect is extremely rare. The indocyanine green retention rate at15 min (ICGR15) is important for estimating hepatic functional reserve and selection of the appropriate surgical procedure before hepatectomy is performed. Because of the rarity of constitutional ICG excretory defect, its clinical features are not well understood. We report here evaluation and treatment of a patient with such a disorder. PRESENTATION OF CASE: An 83-year-old man was admitted to hospital with the diagnosis of resectable hepatocellular carcinoma. The preoperative indocyanine green (ICG) retention rate at 15 min was greater than 76.2%. Despite this finding, Child-Pugh classification and 99mTc-galactosyl human serum albumin (GSA) liver scintigraphy didn't show any abnormal findings, and there was no background disease. Therefore, we diagnosed him with constitutional ICG excretory defect and performed partial hepatectomy. For patients requiring hepatectomy with this disease the indications and procedure for surgery should be considered. These should be based on liver function tests such as GSA liver scintigraphy. CONCLUSIONS: Constitutional ICG excretory defect is an extremely rare disorder. At present, the indications for surgery for this condition should be comprehensively considered. Findings of liver function tests, such as a general liver function test and GSA liver scintigraphy, are important for treating this disorder.

Esophageal Large-Cell Neuroendocrine Carcinoma with Inconsistent Response to Treatment in the Primary and Metastatic Lesions.

Esophageal large-cell neuroendocrine carcinoma (NEC) is a rare malignant tumor that is characterized by high-grade malignancy and a poor prognosis. However, the rarity of esophageal NEC has prevented the development of an established treatment, and no reports have described a discrepancy in the effectiveness of cisplatin plus irinotecan between primary and metastatic lesions. A 43-year-old Japanese man was referred to our hospital with refractory epigastralgia. A previous gastrointestinal endoscopy had revealed a 50-mm type 2 tumor in the abdominal esophagus. The pathological findings indicated poorly differentiated squamous cell carcinoma. Contrast-enhanced computed tomography revealed a metastatic liver tumor. One cycle of fluorouracil and cisplatin was not effective, and endoscopy was repeatedly performed. The pathological findings indicated a large-cell malignant tumor with tumor cells that were positive for CD56, synaptophysin, and Ki-67 (> 80%). Based on a diagnosis of esophageal large-cell NEC with a metastatic liver tumor, the patient received cisplatin plus irinotecan biweekly. After 4 months, computed tomography revealed marked shrinkage of the metastatic tumor, but the patient complained of dysphagia. Endoscopy revealed enlargement of the primary tumor, which was then treated using radiotherapy plus fluorouracil and cisplatin. The primary tumor subsequently shrank, and the patient's symptoms were relieved, but the metastatic tumor grew. Thus, chemoradiotherapy could be an option for managing a primary esophageal large-cell NEC that does not respond to chemotherapy alone. However, the possibility of an inconsistent response to therapy in primary and metastatic lesions should be considered.

Cytological features of hepatoid adenocarcinoma of the gallbladder: A case report with immunocytochemical analyzes.

Hepatoid adenocarcinoma is defined as an extrahepatic malignant neoplasm showing morphological and immunohistochemical resemblance of hepatocellular carcinoma. The occurrence of this type of tumor in the gallbladder is extremely rare. In this study, we report the first cytological case of hepatoid adenocarcinoma of the gallbladder. An 80-year-old Japanese female was found to have a tumorous lesion in the gallbladder. Papanicolaou smear of the ascites demonstrated a few epithelial cell clusters composed of round to oval neoplastic cells with distinct cell border and large centrally-located nuclei. Tumor touch smear of the resected tumor revealed the presence of two distinct neoplastic components. The first component was composed of clusters or sheets of epithelial cells with distinct cell border, relatively rich clear cytoplasm, and centrally-located nuclei, as seen in the ascites specimen. The other component was composed of tall columnar cells with large basally-oriented nuclei, and glandular formation was noted as well. Immunocytochemical analyzes of the touch smear material demonstrated that the former component was positive for HepPar1, thus it was considered as a hepatoid adenocarcinoma, and the latter component deemed as a typical adenocarcinoma. Histopathological and immunohistochemical examination of the resected gallbladder tumor confirmed a diagnosis of hepatoid adenocarcinoma. The characteristic cytological features of hepatoid adenocarcinoma are the presence of sheets or clusters of neoplastic cells with distinct cell border and centrally-located nuclei. Immunocytochemical analysis for HepPar1 may help its diagnosis. Demonstration of hepatoid adenocarcinoma is important in the cytological specimen because this type of tumor shows an aggressive clinical course.

Thymic enteric type adenocarcinoma: A case report with cytological features.

Primary thymic adenocarcinoma is an extremely rare tumor, and thymic enteric type adenocarcinoma has recently been proposed as a distinct pathological entity. Herein, we report the first cytological description of thymic enteric type adenocarcinoma. A 29-year-old Japanese female without a significant past medical history was found to have an abnormal chest shadow. Chest computed tomography demonstrated a well-circumscribed tumor in the anterior mediastinum, and thymectomy was performed. The Papanicolaou staining of the touch smear of the resected tumor demonstrated tightly cohesive epithelial cell clusters in a necrotic background. These cells were cuboidal to columnar in shape and had large round to oval nuclei with conspicuous nucleoli. Some of these neoplastic cells had intracytoplasmic mucin. Immunocytochemically, the neoplastic cells were positive for cytokeratin 20 and CDX-2. Histopathological study revealed tubular and papillotubular neoplastic growth composed of cuboidal to columnar neoplastic cells that contained large round to oval nuclei. Some of the neoplastic cells had intracytoplasmic mucin. Immunohistochemical study confirmed the expression of cytokeratin 20 and CDX-2. The final diagnosis of thymic enteric type adenocarcinoma was made. The cytological and immunocytochemical features of this case led to a diagnosis of enteric type adenocarcinoma. However, these features alone cannot be differentiated from a metastatic adenocarcinoma arising from the gastrointestinal tract. Cytological examination of a fine-needle aspiration of the mediastinal tumor has been reported to be useful in making a diagnosis. Therefore, an awareness of this new pathological entity is important for differentiating a thymic tumor from a metastatic carcinoma in the thymus.

Clinicopathologic Diversity of Undifferentiated Sarcoma With BCOR-CCNB3 Fusion: Analysis of 11 Cases With a Reappraisal of the Utility of Immunohistochemistry for BCOR and CCNB3.

Undifferentiated sarcoma harboring the BCOR-CCNB3 fusion is characterized by its predilection to affect skeletons of adolescent males, cellular small round/spindle cell morphology, and CCNB3 immunoreactivity. We analyzed 11 cases of BCOR-CCNB3 sarcoma, 10 of which were identified in a reverse transcription-polymerase chain reaction-based screen of 85 patient samples recorded in our database as unclassified small round or spindle cell sarcomas. BCOR rearrangements were confirmed by fluorescence in situ hybridization in 8 tumors. All patients were males aged between 6 and 31 years. In addition to 5 tumors in soft tissue and 4 in the axial or appendicular skeletons, which are typical locations, a tumor was located in the paranasal sinus and another in the lung. Microscopically, the tumors comprised proliferating atypical spindle and/or small round cells with diverse morphologic features such as small concentric whorls, myxoid stroma, a hemangiopericytomatous appearance, and/or hyalinized collagen resembling a solitary fibrous tumor, and angiomatous or slit-like spaces containing extravasated erythrocytes. Tumor cells were immunoreactive to CCNB3 (9/11), BCOR (10/10), TLE1 (6/10), bcl-2 (9/11), CD99 (8/10), CD56 (8/10), c-kit (4/10), and cyclin D1 (10/10). In an immunohistochemical analysis of an additional 412 small round or spindle cell tumors, CCNB3 was detected in 6 (1.5%) and BCOR in 18 (4.4%). Our analysis highlights the varying clinicopathologic features of this tumor, which partially overlap with other small round or spindle cell tumors, including solitary fibrous tumor and vascular tumors. Because CCNB3 and BCOR immunohistochemistry lacks adequate sensitivity and specificity, a molecular genetic approach remains essential for diagnosis.