High single-pass diagnostic yield of a new 25-gauge core biopsy needle for EUS-guided FNA biopsy in solid pancreatic lesions.

BACKGROUND: Current limitations of EUS-guided FNA include the need for multiple passes and on-site cytology assessment and lack of core specimen. Recently, a new 25-gauge core biopsy needle (PC25) was developed to overcome these limitations. OBJECTIVE: To determine the diagnostic yield of EUS-guided FNA aspiration biopsy (FNAB) when using the PC25 needle among patients with solid pancreatic lesions. DESIGN: Retrospective analysis. SETTING: Academic tertiary referral center. PATIENTS: Fifty consecutive patients with a solid pancreatic lesion underwent EUS-guided FNAB with PC25. INTERVENTIONS: EUS-guided FNAB with PC25. MAIN OUTCOME MEASUREMENTS: The primary outcome was the diagnostic yield in single and overall passes of EUS-guided FNAB when using the PC25 needle for pancreatic solid lesions. RESULTS: Cytologic analysis showed malignancy in 38 patients on the first pass, with a cumulative sensitivity of 83%, 91%, and 96% on passes 1, 2, and 3, respectively. Although visible core was reported in 46 patients (92%), histologic core was seen in 16 patients (32%). Histologic analysis showed malignancy in 29 patients on the first pass, with a cumulative sensitivity of 63% and 87% on pass 1 and passes 1 to 4, respectively. The sensitivity, specificity, and accuracy in combined cytologic and histologic results were 85%, 100%, and 86% for single pass and 96%, 100%, and 96% on multiple passes, respectively. No complications were seen. LIMITATIONS: A retrospective study design at a single center using a single arm. CONCLUSION: EUS-guided FNAB with the PC25 needle showed excellent single-pass and overall diagnostic yields. This needle appears to maintain a high cytologic yield, similar to standard 25-gauge FNA needles, while also providing some histologic core tissue.

Cytologic diagnosis of chordoma in a peritoneal effusion: a case report.

BACKGROUND: Chordoma, a distinct malignant neoplasm arising from the remnants of the notochord, occurs mostly in patients in the fifth to seventh decade of life. Metastasis occurs in 20-30% of cases. The most common metastatic sites are lungs and, less commonly, other bones and visceral organs. The cytologic features of chordoma in both primary and metastatic foci have been described for specimens obtained by fine needle aspiration biopsy. A few cases have been reported in the sputum and the cerebrospinal fluid. CASE: A 57-year-old man presented with metastatic chordoma diagnosed in a peritoneal effusion. Cytospin slides of the effusion showed numerous individual and clusters of polygonal, round epithelial cells with a background of myxoid chondroid substance, which stained metachromatic on Diff-Quik slides. Many diagnostic physaliphorous cells were present and characterized by abundant intracytoplasmic vacuoles of various sizes. The nuclei were monotonous, with minimal anisonucleosis. The nuclei had evenly dispersed chromatin with occasional small, eosinophilic nucleoli. The nuclear membranes were smooth, with focal indentation. The differential diagnosis included an adenocarcinoma and metastatic chordoma. Immunohistochemistry applied to the cell block showed that the neoplastic cells were positive for cytokeratin and S-100 protein. CONCLUSION: The clinical history with immunohistochemical profiles helped confirm the diagnosis of metastatic chordoma.

Radical surgical cytoreduction of progressive leiomyomatosis peritonealis disseminata: a case report.

BACKGROUND: Leiomyomatosis peritonealis disseminata (LPD) is an uncommon, benign smooth muscle condition of the peritoneal cavity that appears clinically as a metastatic malignant neoplasm. Generally, radical surgery is not recommended. This unique case involves curative radical surgery after disease progression during depo-medroxyprogesterone acetate therapy. In vitro assays and future implications are discussed. CASE: A 31-year-old woman presented with abdominal pain and uterine leiomyomas. During exploratory laparotomy, she had gross evidence of LPD. Despite initial surgery and hormonal therapy, she had progression of disease. She then underwent optimal cytoreductive surgery. Tumor response to megestrol acetate in vitro was evaluated and noted to be heterogeneous; therefore it was not given as adjuvant therapy. Five years after radical surgery, she was without evidence of disease, CONCLUSION: Radical secondary cytoreductive surgery can achieve a durable remission for LPD refractory to primary surgical castration and depomedroxyprogesterone acetate therapy.

Cytologic diagnosis of hemophagocytic lymphohistiocytosis in ascitic fluid: a case report.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH), also known as macrophage activation syndrome, is a rare, fatal hematopoietic disease. Its cytologic features may be subtle because the abnormal histiocytes may not be recognized if one is not aware of this entity. We report a case of HLH involving the ascitic fluid. CASE REPORT: A 73-year-old man developed weakness, lethargy, decreased appetite and progressive shortness of breath after a cholecystectomy. Physical examination revealed hypotension, tachycardia and chest dullness with decreased breath sounds bilaterally. Radiologic examination revealed bilateral pleural effusions. The patient accumulated fluid in the peritoneal cavity, lungs, retroperitoneum and mediastinum. Bone marrow biopsy showed abundant histiocytes infiltrating the marrow cavity, and many of these histiocytes contained cellular debris. A diagnosis of HLH was therefore made. The abdominal paracentesis specimen contained many similar histiocytes exhibiting erythrophagocytosis and lymphophagocytosis. These abnormal histiocytes were positive for CD68 and negative for AE1/AE3, confirming the diagnosis of HLH. The patient died soon after from disseminated aspergillosis. CONCLUSION: HLH is cytologically characterized by the presence of abnormal histiocytes with ingested cellular debris. In serous effusions they should not be confused with mesothelial cells. Immunohistochemical studies may help confirm the diagnosis.

Endoscopic ultrasound-guided fine-needle aspiration of undifferentiated carcinoma with osteoclast-like giant cells of the pancreas: a report of 2 cases with literature review.

Undifferentiated carcinoma with osteoclast-like giant cells of the pancreas is rare. Histologically it mimics the giant cell tumor of the bone and may be associated with a ductal adenocarcinoma. We recently encountered two such cases, both of which were biopsied by EUS-guided FNA. Abundant multinucleated osteoclast-like giant cells and many uniform mononuclear cells were present in case 1 so that the diagnosis was made. In case 2, many mononuclear tumor cells with vacuolated and basophilic cytoplasm were present, and rare osteoclast-like giant cells were seen. A diagnosis of adenocarcinoma was made. In both cases, no conspicuous nuclear pleomorphism was noted in the mononuclear cells or the multinucleated giant cells. The histology of case 2 revealed a pure undifferentiated carcinoma with osteoclast-like giant cells. In addition, a liver biopsy revealed globular amyloidosis. To our knowledge, this is the first report of pancreatic undifferentiated carcinoma with osteoclast-like giant cells sampled by EUS-guided FNA and the first case of hepatic globular amyloidosis associated with this tumor.

Cytologic diagnosis of mastocytosis by fine needle aspiration biopsy: a case report.

BACKGROUND: Mastocytosis is an abnormal proliferation of mast cells and their subsequent accumulation in various organs. Diagnosis of mast cell disease relies on proper identification of abnormal mast cells. CASE: A 55-year-old man presented with a history of fever for several months, associated with night sweats, involuntary 20lb weight loss, progressive fatigue, weakness, worsening abdominal distention, shortness of breath, and diffuse lymphadenopathy. Physical examination and computed tomography (CT) showed hepatosplenomegaly, massive ascites, and generalized lymphadenopathy. Bone marrow biopsy with immunohistochemistry (ICH) studies revealed mastocytosis. CT-guided fine needle aspiration biopsy (FNAB) of the retroperitoneal lymphadenopathy was performed. The smears were cellular for a mixed population of mature plasma cells, eosinophils, left-shifted granular and lymphoid cells, and abundant abnormal mast cells. The mast cells had round to oval lobulated nuclei, some of which were binucleated or eccentrically located, with coarse, evenly distributed chromatin. Abundant pale cytoplasm contained numerous metachromatic granules. IHC studies and flow cytometry confirmed the cytologic diagnosis of mastocytosis. CONCLUSION: This case highlights the cytologic features of mastocytosis in FNA specimens. IHC stains and flow cytometry are helpful to confirm the cytologic diagnosis. To the best of our knowledge, this is the second case that describes the cytologic characteristics of mastocytosis.

Burkitt's lymphoma of the base of the tongue: a case report and review of the literature.

Burkitt's lymphoma is a highly aggressive, mature B cell non-Hodgkin's lymphoma that is rare outside Africa. We report a case of Burkitt's lymphoma presenting as a rapidly expanding tongue-base mass that caused airway obstruction in an 80-year-old Palestinian man living in California. According to our review of the literature, this is only the third reported case of Burkitt's lymphoma arising in the base of the tongue. We also discuss the incidence, epidemiology, genetics, prognosis, and treatment of this malignancy. Because Burkitt's lymphoma is one of the fastest-growing tumors in humans, rapid diagnosis and treatment are important. Treatment involves brief-duration, high-intensity chemotherapy and central nervous system prophylaxis. It is important for the otolaryngologist to recognize this disease and to understand the steps necessary to treat this aggressive tumor.

Optical coherence tomography of laryngeal cancer.

OBJECTIVES: Optical coherence tomography (OCT) is a high-resolution optical imaging technique that produces cross-sectional images of living tissues using light in a manner similar to ultrasound. This prospective study evaluated the ability of OCT to identify the characteristics of laryngeal cancer and measure changes in the basement membrane, tissue microstructure, and the transition zone at the edge of tumors. MATERIALS AND METHODS: One hundred thirty-three patients underwent OCT examination during surgical endoscopy of the head and neck. Twenty-two patients with laryngeal cancer or a history of laryngeal cancer were imaged with a fiberoptic OCT system. Tumor and adjacent transition zones were imaged along with uninvolved subsites. OCT images were correlated with histopathology. RESULTS: Twenty-six OCT examinations were performed in 22 patients. Basement membrane disruption was seen in 18 subjects, all of whom had histology showing classic features of cancer. A transition zone to uninvolved epithelium at the tumor periphery was also often observed. In six studies, benign or premalignant processes were histologically confirmed. In three thin, superficial lesions, an intact basement membrane was observed. The basement membrane could not be identified in three other bulky exophytic, premalignant lesions, primarily because of increased superficial signal backscattering observed in pathologic tissues. CONCLUSIONS: OCT clearly identifies basement membrane violation from laryngeal cancer and can identify transition zones at the cancer margin. In bulky exophytic lesions, OCT signal may not penetrate deeply enough to show the basement membrane, but for many suspicious lesions that require exclusion of cancer, OCT shows potential for assisting in diagnostic assessment.

In vivo optical coherence tomography of the human oral cavity and oropharynx.

Optical coherence tomography (OCT) is an evolving imaging modality that combines interferometry with low-coherence light to produce high-resolution tissue imaging. Cross-sectional in vivo images were obtained using an OCT device consisting of a Michelson interferometer, 1.3-microm broadband light source, and a handheld fiberoptic imaging probe. Image pixel resolution approached 10 microm. The mucosa of the oral cavity and oropharynx were examined in 41 patients during operative endoscopy. Optical coherence tomographic imaging was combined with endoscopic photography for gross and histologic image correlation. Optical coherence tomographic images of the oral cavity and oropharynx provided microanatomical information on the epithelium, basement membrane (BM), and supporting lamina propria (LP) of the mucosa. Normal microstructures identified in these tissues included an overlying keratin layer, papillae, ducts, glands, and blood vessels. Regions of pathologic features studied included mature scar, granulation tissue, mucous cysts, leukoplakia, and invasive cancer. Optical coherence tomographic imaging showed distinct zones of normal, altered, and ablated tissue microstructures for each pathologic process studied. Abnormal findings were directly compared with regions of normal tissue or conventional histopathologic features when tissue for analysis was available. This study provides a composite series of in vivo OCT images of the oral cavity and oropharynx in a variety of normal regions and pathologic states as well as outline future applications of OCT technology.

Eccrine porocarcinoma: Report of a case with fine needle aspiration cytology, histopathology and immunohistochemistry.

BACKGROUND: Although relatively rare, eccrine porocarcinoma (EP) is widely recognized in the literature as the most common of the sweat gland adenocarcinoma types. EP is an adenocarcinoma of the eccrine sweat gland with a propensity to recur locally and metastasize to regional lymph nodes. This paper presents the second case of fine needle aspiration (FNA) cytology of an EP along with histopathology and immunohistochemistry. CASE: A 64-year-old Filipino woman had a history of EP of the right eyebrow and presented with a right preauricular mass. The cytopathologic features of the case included: (1) clusters and sheets of polyhedral epithelial tumor cells with abundant, cyanophilic, vacuolated cytoplasm; round to oval, hyperchromatic nuclei; and occasional prominent nucleoli; (2) multinucleated tumor cells; (3) singly dispersed and relatively large aggregates of parakeratotic squamous cells; and (4) a background of necrotic debris. CONCLUSION: EP is crucial to developing an effective (curative) surgical plan. FNA cytology potentially provides a convenient, safe and effective approach to solving a challenging differential diagnosis. The constellation of cytologic findings probably is distinctive and, in the proper clinical setting, may be diagnostic. History is important in making an accurate diagnosis.

In vivo optical coherence tomography of the human larynx: normative and benign pathology in 82 patients.

OBJECTIVES: Optical coherence tomography (OCT) is an emerging imaging modality that combines low-coherence light with interferometry to produce cross-sectional images of tissue with resolution about 10 mum. Patients undergoing surgical head and neck endoscopy were examined using a fiberoptic OCT imaging probe to study and characterize microstructural anatomy and features of the larynx and benign laryngeal pathology in vivo. STUDY DESIGN: Prospective clinical trial. MATERIALS AND METHODS: OCT imaging of the larynx was performed in 82 of 115 patients who underwent surgical endoscopy for various head and neck pathologies. The OCT device employs a 1.3 microm broadband light source (FWHM, 80 nm). The frame rate is 1 Hz. Imaging was performed using a handheld probe placed in near contact with the target site. The maximum axial and lateral dimensions for the region of interest imaged were 2.5 mm x 6 mm, with resolutions of 10 microm. Simultaneously, conventional endoscopic images were obtained to provide anatomic correlation with OCT images and histology. Optical micrometry was performed to measure the epithelium thickness. RESULTS: Systematic OCT imaging of laryngeal structures and subsites provided information on the thickness of the epithelium, integrity of the basement membrane, and structure of the lamina propria. Microstructural features identified included glands, ducts, blood vessels, fluid collection/edema, and the transitions between pseudostratified columnar and stratified squamous epithelium. The mean epithelial thickness of laryngeal subsites was calculated: true vocal cord (129 microm), false vocal cords (124 microm), aryepiglottic fold (177 microm), subglottis (98 microm), and epiglottis (185 microm). True vocal cord pathology imaged included Reinke's edema, papillomatosis, polyps, mucous cysts, and granulation tissue. Subglottic imaging identified boundaries between epithelium, lamina propria, and cartilage. The OCT images compared favorably with conventional histopathology. CONCLUSION: OCT has the unique ability to image laryngeal tissue microstructure and can detail microanatomic changes in benign, premalignant, and malignant laryngeal pathologies. OCT holds the potential to guide surgical biopsies, direct therapy, and monitor disease, particularly when office-based systems are developed. This is a promising imaging modality to study the larynx.

Pap smears of patients with extramammary Paget's disease of the vulva.

Extramammary Paget's disease (EMPD) of the vulva is a rare entity. The diagnosis is almost always made on biopsy. Tumor cells are seen rarely in Papanicolaou (Pap) smears. We encountered three cases of EMPD that were detected in Pap smears. One patient had vulvar and vaginal involvement and the abnormal cells seen in the vaginal smear initially were interpreted as high-grade squamous intraepithelial lesion. Retrospective review showed scattered single atypical cells with enlarged hyperchromatic nuclei, coarse chromatin, inconspicuous nucleoli, high nuclear/cytoplasmic (N:C) ratio, and scanty basophilic cytoplasm. Rare signet ring cells and cells within cells were present. In the other two patients who had cervical involvement, the correct diagnosis was made on Pap smears. The slides showed both single and cohesive sheets of glandular cells with enlarged round to oval nuclei, coarse chromatin, prominent nucleoli, and abundant basophilic cytoplasm containing prominent vacuoles with signet ring-cell appearance. Cells within cells were abundant. EMPD has distinct cytomorphological features. Although infrequently encountered, EMPD can be diagnosed on Pap smears with adequate clinical history.

Cytological diagnosis of endocrine tumors of the pancreas by endoscopic ultrasound-guided fine-needle aspiration biopsy.

The aim of this study was to evaluate the efficacy and accuracy of endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) in the diagnosis of pancreatic endocrine tumors and to analyze their cytomorphology. Between March 1999 and June 2004, a total of 30 patients with a cytological diagnosis of pancreatic endocrine tumors were found. Their records were retrieved and the cytological materials were analyzed. The mean size of the tumors assessed by EUS was 3.0 cm. Immediate preliminary interpretation was rendered after an average of 1.5 passes. Based on the cellular patterns, cases were divided into three categories: loosely cohesive aggregates, discohesive single cells, and cohesive flat sheets. Most tumor cells had abundant cytoplasm and eccentric nuclei. Chromatin was fine or coarse but was evenly distributed in all cases. Nuclear pleomorphism, multinucleation, intranuclear inclusions, mitotic figures, and necrosis were seen. Immunohistochemical (IHC) studies on cell blocks confirmed the diagnosis in all cases. EUS-guided FNA is efficient and accurate in establishing the diagnosis of pancreatic endocrine tumors. The variety of cellular patterns presents several differential diagnostic issues that should be considered to avoid erroneous interpretation.

Fluorescence in situ hybridization for HER-2/neu amplification of breast carcinoma in archival fine needle aspiration biopsy specimens.

OBJECTIVE: To assess the usefulness of fluorescence in situ hybridization (FISH) for HER-2/neu amplification of breast carcinoma in archival fine needle aspiration biopsy (FNAB) specimens. STUDY DESIGN: All FISH performed on formalin-fixed, paraffin-embedded surgical specimens during January 2003-August 2003 at the University of California Irvine Medical Center were selected. Prior FNABs were retrieved. One cytologic slide was destained in each case. The results were compared with those obtained on histologic specimens using the paired t test. RESULTS: FISH was performed on 41 surgical specimens of breast carcinoma. Thirteen patients had prior FNABs that were positive for adenocarcinoma. After hybridization on destained fine needle aspiration slides, no cells were found in 2 cases, and the results were not readable in 2 cases. In the remaining 9 cases, the results, expressed as the ratio of copies of the HER-2/neu gene to copies of the chromosome 17 centromere, were 5.10, 1.14, 1.21, 1.12, 0.74, 1.11, 1.21, 9.87 and 2.4. Results on the corresponding histologic specimens were 5.25, 1.05, 1.13, 1.22, 1.13, 1.12, 1.21, 9.35 and 2.61, respectively. No significant difference was found (p = 0.23). CONCLUSION: HER-2/neu amplification status by FISH can be accurately and reliably evaluated in existing archival cytologic slides.

Efficacy of cone biopsy of the uterine cervix during frozen section for the evaluation of cervical intraepithelial neoplasia grade 3.

We retrospectively selected 22 cases in which patients with a biopsy-proven diagnosis of cervical intraepithelial neoplasia grade 3 underwent cervical conization for frozen section (FS) evaluation followed by hysterectomy at the University of California Irvine Medical Center, Orange, during the August 1995 to September 9, 2001. All slides from FS and permanent section (PS) and hysterectomy specimens were reviewed. FS diagnoses were compared with those of previous biopsies, PS, and hysterectomy specimens. The PS correlated with FS in all cases but 1. Appropriate surgery was performed for all patients based on FS diagnosis. The McNemar test was used to compare the results of FS and PS, with a 2-sided P value of 1.0 and a c coefficient of 0.7755 with a 95% confidence level, indicating that the 2 groups were not significantly different. FS evaluation of cervical conization is as efficacious and accurate as evaluation of regular specimens in providing information for the appropriateness of same-day surgery. We recommend that entire tissue be submitted for FS to avoid sampling errors and to increase diagnostic accuracy.

Pancreatic schwannoma. A case report and review of the literature.

CONTEXT: Pancreatic schwannomas are rare neoplasms. These tumors vary in size and two thirds are partially cystic which grossly mimic pancreatic cystic lesions. Computed tomography and magnetic resonance imaging are the primary initial imaging modalities. Definitive diagnosis is typically made at the time of laparotomy following biopsy. Surgical resection is the mainstay of treatment. CASE REPORT: A 69-year-old woman presented with abdominal pain in the epigastric and left upper quadrant. The patient had no systemic symptom and laboratory results including tumor markers were negative. A CT scan of the abdomen showed a 5 cm mass arising from the head of the pancreas. Needle biopsy revealed a mass consistent with schwannoma. At laparotomy, a large pancreatic head mass was found to encase the superior mesenteric artery, and portal vein confluence. Frozen biopsy showed schwannoma. Curative resection was deferred due to extensive vascular involvement and favorable tumor biology. A gastrojejunostomy was performed and radiation therapy was instituted post-operatively. CONCLUSIONS: Only 24 cases of pancreatic schwannoma had been previously reported. Definitive diagnosis is obtained with routine histology. Most tumors are benign and surgical resection is curative. The role of radiation therapy in the management of unresectable tumors is still unclear.

Malignant phyllodes tumor of the breast metastatic to the parotid gland diagnosed by fine needle aspiration biopsy. A case report.

BACKGROUND: Phyllodes tumor (cystosarcoma phyllodes) is a rare fibroepithelial neoplasm of the breast. Malignant phyllodes tumor is characterized by an infiltrative border and marked degree of hypercellular stromal overgrowth with > 5 mitoses per 10 high-power fields. Distant metastasis occurs in 10-20% of patients with malignant phyllodes tumor. The most common sites of distant metastases are the lungs, bone and abdominal viscera. Although theoretically any organ may have metastasis, the parotid gland has not been documented before in the English-language literature. CASE: A 40-year-old, Caucasian woman with a history of malignant phyllodes tumor of the left breast presented with a mass on the right side of the parotid gland. Fine needle aspiration biopsy of the mass revealed abundant discohesive spindle cells showing moderate nuclear pleomorphism with occasional mitoses. No epithelial elements were seen. A diagnosis of malignant spindle cell tumor consistent with metastatic malignant phyllodes tumor was made. Histology confirmed the cytologic diagnosis. CONCLUSION: Fine needle aspiration biopsy is accurate and efficient in conjunction with clinical information in the diagnosis of malignant phyllodes tumor of the breast metastatic to the parotid gland.

Diagnosis of gastric glomus tumor by endoscopic ultrasound-guided fine needle aspiration biopsy. A case report with cytologic, histologic and immunohistochemical studies.

BACKGROUND: The majority of glomus tumor are small, benign neoplasms that arise from modified smooth muscle cells. They usually occur in the dermis or subcutis of the extremities. However, rare cases have been reported in the visceral locations, most often in the stomach. CASE: A 32-year-old woman presented with episodes of right upper quadrant pain. She was found to have a gastric tumor that was biopsied at another hospital, where the diagnosis of gastrointestinal stromal tumor (GIST) was made. Endoscopic ultrasound (EUS) performed at our institution revealed a gastric submucosal tumor that was then biopsied by fine needle aspiration (FNA). Cytology revealed cohesive clusters of uniform, round, small cells with ill-defined cytoplasmic borders and scanty, amphophilic cytoplasm. Nuclei were round, with smooth nuclear membranes and evenly distributed, dusty chromatin. Intermingled with those epithelioid cells were small, short, spindled, normal endothelial cells. Immunohistochemical studies performed on cell block showed that the tumor cells were negative for CD34, CD117, chromogranin, synaptophysin, desmin and AE1/AE3 and were strongly positive for SMA, HHF-35 and collagen type IV. Glomus tumor was diagnosed and later confirmed by histology. CONCLUSION: EUS-guided FNA biopsy is efficient and permits adequate sampling for accurate diagnosis of gastric glomus tumor. Although rare, glomus tumor should be in the differential diagnosis among other gastric lesions, such as well-differentiated adenocarcinoma, epithelioid GIST and carcinoid tumor.

Cytologic features of lipid-rich variant of pancreatic endocrine tumor-report of two cases with literature review.

Pancreatic endocrine tumor (PET) is an uncommon neoplasm of the pancreas with distinct cytomorphologic features. Lipid-rich PET, a rare variant, histologically deviates from that of a conventional PET. There is only one case report of the cytologic features of this rare entity in the literature. We report two cases of lipid-rich PETs diagnosed by endoscopic ultrasound-guided FNA biopsy. Case 1 showed large aggregates, small clusters, and single cells with plasmacytoid appearance, small uniform nuclei, coarse chromatin, and prominent nucleoli. Abundant distinct small cytoplasmic vacuoles were present in almost all tumor cells and the background was clean. Case 2 showed flat cohesive sheets of medium-sized uniform cells with indistinct plasmacytoid appearance, uniform nuclei, fine and evenly distributed chromatin, and inconspicuous nucleoli. Distinct small cytoplasmic vacuoles were seen only focally. Immunohistochemical stains in cell blocks of both cases confirmed the diagnosis of PET. Lipid-rich PET may be misinterpreted on cytology specimens if the pathologist is not aware of this rare entity since it mimics clear cell carcinoma of the kidney, adrenal cortical neoplasm, or adenocarcinoma of the pancreas.

Cytopathologic, histopathologic, and immunohistochemical features of intrahepatic clear cell bile duct adenoma: a case report and review of the literature.

Intrahepatic clear cell bile duct adenoma is extremely rare, with only 3 previous cases reported in the literature. The cause of cytoplasmic clearing in clear cell bile duct adenoma has not been previously investigated. Distinguishing clear cell bile duct adenoma from other clear cell tumors, particularly clear cell cholangiocarcinoma, can be challenging. Previous studies have shown loss of CD10 expression and focal CD56 expression in cholangiocarcinoma. Expressions of CD10 and CD56 have not been previously studied in clear cell bile duct adenoma. A 37-year-old morbidly obese woman was diagnosed with a 2.8 cm intrahepatic clear cell bile duct adenoma following segmental hepatic resection. Histochemical analysis of the tumor suggested the cause of cytoplasmic clearing in the neoplastic cells to be mucin and not glycogen or lipid. On immunohistochemical staining, the neoplastic cells demonstrated staining for CK7, CA 19-9, polyclonal CEA, CD10 (apical), CD56 (focal), and vimentin. Ki-67 highlighted less than 2% of tumor cell nuclei. This is the first report to study the etiology of cell clearing in clear cell bile duct adenoma. Expression of CD10 in clear cell bile duct adenoma may help distinguish clear cell bile duct adenoma from clear cell cholangiocarcinoma.