Prognostic significance of gross extrathyroidal extension invading only strap muscles in differentiated thyroid carcinoma.

BACKGROUND: In the eighth edition of the AJCC staging system for differentiated thyroid carcinoma (DTC), minimal extrathyroidal extension (ETE) is no longer a determinant of T3 category. Instead, gross ETE invading only strap muscles has been designated as a new T3b category. The long-term prognosis of patients with DTC and gross ETE invading only strap muscles was investigated. METHODS: This was a retrospective analysis of patients who underwent thyroidectomy between 1996 and 2005. Differences in cancer-specific and recurrence-free survival according to extent of ETE were assessed. RESULTS: A total of 3174 patients with DTC were included. No significant differences were observed in 10-year cancer-specific survival among patients with no ETE (98·6 per cent), microscopic ETE (98·3 per cent) and gross ETE invading only strap muscles (98·9 per cent) (P = 0·375). The 10-year recurrence-free survival rate for patients with gross ETE invading only strap muscles (89·2 per cent) was shorter than that for patients with no ETE (93·7 per cent; P = 0·016), but similar to that of patients with microscopic ETE (90·3 per cent). In univariable analysis, patients with gross ETE invading only strap muscles had a significantly higher risk of recurrence than those with no ETE (hazard ratio (HR) 1·67, 95 per cent c.i. 1·10 to 2·55; P = 0·017). In multivariable analysis, gross ETE invading only strap muscles was not an independent predictor of recurrence (HR 1·09, 0·71 to 1·69; P = 0·685). CONCLUSION: Although gross ETE invading only strap muscles may provide prognostic information about long-term recurrence, it does not affect mortality. The actual impact of gross ETE invading only strap muscles will be important in revising the staging system in the future.

Histogram analysis of greyscale sonograms to differentiate between the subtypes of follicular variant of papillary thyroid cancer.

AIM: To evaluate the diagnostic value of histogram analysis using ultrasound (US) to differentiate between the subtypes of follicular variant of papillary thyroid carcinoma (FVPTC). MATERIALS AND METHODS: The present study included 151 patients with surgically confirmed FVPTC diagnosed between January 2014 and May 2016. Their preoperative US features were reviewed retrospectively. Histogram parameters (mean, maximum, minimum, range, root mean square, skewness, kurtosis, energy, entropy, and correlation) were obtained for each nodule. RESULTS: The 152 nodules in 151 patients comprised 48 non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTPs; 31.6%), 60 invasive encapsulated FVPTCs (EFVPTCs; 39.5%), and 44 infiltrative FVPTCs (28.9%). The US features differed significantly between the subtypes of FVPTC. Discrimination was achieved between NIFTPs and infiltrative FVPTC, and between invasive EFVPTC and infiltrative FVPTC using histogram parameters; however, the parameters were not significantly different between NIFTP and invasive EFVPTC. CONCLUSION: It is feasible to use greyscale histogram analysis to differentiate between NIFTP and infiltrative FVPTC, but not between NIFTP and invasive EFVPTC. Histograms can be used as a supplementary tool to differentiate the subtypes of FVPTC.

What Is the Ideal Core Number for Ultrasonography-Guided Thyroid Biopsy of Cytologically Inconclusive Nodules?

BACKGROUND AND PURPOSE: Core needle biopsy of the thyroid under ultrasonographic guidance provides a larger tissue sample and may facilitate a more precise histologic diagnosis, reducing the need for repetitive fine-needle aspiration or a diagnostic operation. However, there is no consensus regarding the ideal number of specimens to be obtained for ultrasonography-guided core needle biopsy. The aim of this study was to decide the ideal core number for ultrasonography-guided core needle biopsy of cytologically inconclusive nodules. MATERIALS AND METHODS: Sixty consecutive biopsies were performed in 60 thyroid nodules with Bethesda Category I or III cytology. Three biopsy cores were obtained for each thyroid nodule. The first biopsy specimens were taken from the nodule, while the second and third specimens obtained included the nodular tissue, nodular capsule, and surrounding parenchyma. Diagnostic ability was evaluated according to the following: protocol A, first specimen; protocol B, first and second specimens; and protocol C, all specimens. The McNemar test was used for statistical analysis. RESULTS: Of the 60 nodules, diagnostic ability was achieved in 41 nodules (68%) with protocol A, in 56 nodules (93%) with protocol B, and in 58 nodules (97%) with protocol C. The diagnostic ability of protocols B and C was significantly higher than that of protocol A (all P values < .001). However, the diagnostic ability of protocol B was not significantly different from that of protocol C. CONCLUSIONS: Ultrasonography-guided core needle biopsy for cytologically inconclusive thyroid nodules should obtain at least 2 core specimens with intranodular and capsule targets.

Modified Core Biopsy Technique to Increase Diagnostic Yields for Well-Circumscribed Indeterminate Thyroid Nodules: A Retrospective Analysis.

BACKGROUND AND PURPOSE: The results of conventional core biopsy for some thyroid nodules with indeterminate cytology have still remained indeterminate. The aim of this study was to evaluate whether the ultrasonography-guided core needle biopsy technique containing the nodule, capsular portion, and surrounding parenchyma was more effective than a conventional method in enhancing diagnostic yield for circumscribed solid thyroid nodules without malignant sonographic features. MATERIALS AND METHODS: This retrospective comparative study evaluated 26 thyroid nodules in 26 consecutive patients between 2006 and 2010. They were biopsied by using a conventional method, and 61 nodules from 60 patients were biopsied by using a modified ultrasonography-guided core needle biopsy technique in 2013. The patients enrolled in this study presented with circumscribed solid thyroid nodules without malignant sonographic features, classified as nondiagnostic or atypia/follicular lesions of undetermined significance at previous cytology. The ultrasonography-guided core needle biopsy results of the 2 groups were compared. RESULTS: The rate of inconclusive ultrasonography-guided core needle biopsy results was 34.6% (9/26) in the conventional group and 11.4% (7/61) in the modified technique group (P = .018). There was no significant difference in the mean size of the nodules between the 2 groups (P = .134). The malignancy rate was 33% (3/9) for the conventional group and 52% (27/52) for the modified technique group (P = .473). The most common malignant pathology was a follicular variant of papillary thyroid carcinoma and follicular adenoma was the most common benign lesion. CONCLUSIONS: For circumscribed solid nodules without malignant sonographic features with indeterminate cytology, the ultrasonography-guided core needle biopsy technique containing the nodule, capsular portion, and surrounding parenchyma is more effective in diagnostic yield compared with a conventional method that biopsies the intranodular portion.

Diagnostic dilemmas of hyalinizing trabecular tumours on fine needle aspiration cytology: a study of seven cases with BRAF mutation analysis.

OBJECTIVE: Hyalinizing trabecular tumours (HTTs) are rare follicular-derived neoplasms that behave in an almost benign manner. HTT is frequently misdiagnosed as papillary carcinoma by fine needle aspiration (FNA) cytology or as papillary or medullary carcinoma on surgical resection. METHODS: The authors examined FNA material from seven cases of histologically verified HTT. Cytological findings were reviewed and correlated with ultrasonographic and histological features. In addition, MIB-1 and calcitonin immunostaining was performed on surgical specimens, and BRAF mutation analysis on three pre-operative FNA specimens and seven histology specimens. RESULTS: The original cytological diagnosis was either suspicious or positive for papillary carcinoma in all patients. The FNA-based differential diagnoses included HTT, papillary carcinoma or, less likely, medullary carcinoma in two patients. Aspirates showed oval to spindle-shaped cells with frequent intranuclear inclusions, isolated in loosely cohesive groups with a trabecular or syncytial pattern in a bloody background. Radiating arrangements of tumour cells surrounding hyaline stroma with serrated calcifications and a lack of papillary or sheet-like fragments may suggest HTT on FNA. Spherical calcified bodies and possible psammoma bodies were frequently found in three cases. Retrospectively, six of the seven cases showed membranous immunoreactivity for MIB-1, but none of the seven possessed the BRAF (V600E) mutation or showed calcitonin reactivity. CONCLUSIONS: Although the recognition of HTT on FNA cytology is difficult, because of its morphological similarities to papillary and medullary carcinoma, its characteristic cytological features along with ultrasonographic findings may suggest the diagnosis preoperatively and avoid surgical over-treatment.

Fine needle aspiration cytology of solitary fibrous tumours of the pleura.

OBJECTIVE: To analyse fine needle aspirates from solitary fibrous tumour (SFT) of the pleura and to elucidate the cytological features unique to these tumours and differential diagnostic findings of benign and malignant SFTs. METHODS: Fine needle aspiration (FNA) cytology slides from eight cases of SFT of the pleura, including six benign and two malignant SFTs, were reviewed. The subsequent histological slides were also examined. RESULTS: Cytological diagnoses from six histologically proven cases of benign SFTs were low-grade sarcoma (one), non-small cell carcinoma (one), malignant tumour (1) and benign (three). Two cases of malignant SFTs were cytologically diagnosed as malignancy. The aspirates showed a varying degree of cellularity. Most smears were composed of single, scattered fusiform cells, and irregular loose aggregates of oval to spindle cells intimately admixed with dense collagenous stroma. Two malignant SFTs had a greater number of cells in clusters, and displayed mitotic activity, without significant cytological atypia. CONCLUSIONS: The diagnosis of SFT may be suggested by a combination of cytological and radiological findings. The precise determination of malignancy for SFT, however, is not usually straightforward on the basis of cytological features alone. The findings of highly cellular clusters and mitotic activity in the FNA cytological smear can help differentiate malignant from benign SFTs.

Cyclosporine-induced apoptosis in osteosarcoma cells.

INTRODUCTION: Posttransplant bone disease is one of the complications of cyclosporine (CsA), which is widely used as an immunosuppressive agent in the field of kidney transplantation. Cyclosporine treatment causes osteopenia as a result of altered bone turnover, but the pathogenic mechanisms of this process remain unclear. This study examined the ability of CsA to induce apoptosis in a rat osteoblast cell line. RESULTS: We induced apoptosis in rat osteoblastic ROS 17/2.8 cells by exposure to CsA. MTT assay showed that CsA exhibited significant cytotoxic effects on ROS 17/2.8 cells in a dose-dependent manner. Western blot analysis showed enhanced processing of caspase-8, Bax, and p53 after CsA treatment. Expression of cleaved poly (ADP-ribose) polymerase (PARP) was elevated by CsA treatment. Pro-caspase-3 and Bcl-2 proteins were decreased by CsA. CONCLUSIONS: These results suggested that CsA induced apoptosis of osteoblasts.

Value of repeat ultrasound-guided fine-needle aspiration in nodules with benign cytological diagnosis.

PURPOSE: To assess the value of repeat ultrasound-guided fine-needle aspiration (US-FNA) in nodules with benign cytological diagnosis. MATERIAL AND METHODS: One-hundred-and-eighty-seven patients undergoing repeat US-FNA were included after a benign cytological diagnosis had been made by the initial US-FNA. They were divided into a re-aspiration group, who underwent repeat US-FNA within 6 months for a discordant pathological and clinico-radiological result, and a follow-up aspiration group, who underwent repeat US-FNA after 6 months without any clinical or radiological suspicion. The cancer rate in each group and the US findings of the later-diagnosed malignant nodules were assessed. RESULTS: Nine malignancies were verified in the 187 cases (4.8%) by repeat US-FNA or surgery. In 44 patients in the re-aspiration group, 6 malignancies were identified (13.6%), compared with 3 malignancies in the 143 patients in the follow-up aspiration group (2.1%) (P<0.05). The later-diagnosed malignant nodules were an average of 1.0 cm in diameter; 66.7% were round; 66.7% were circumscribed; 100% were solid; 88.9% were hypoechoic; and 55.6% contained calcifications on US. CONCLUSION: The follow-up of nodules with benign cytological diagnosis without clinicoradiological suspicion of malignancy is warranted using imaging surveillance rather than repeated US-FNA.

Chromogenic in situ hybridization analysis of HER-2/neu status in cytological samples of breast carcinoma.

The current use of humanized monoclonal antibody trastuzumab for the treatment of patients with metastatic breast cancer has made evaluation of HER-2/neu status an important clinical issue. Chromogenic in situ hybridization (CISH), in which the DNA probe is detected with an immunohistochemistry (IHC)-like peroxidase reaction, has been recently developed for the assessment of HER-2/neu status in formalin-fixed breast cancer specimens. We have applied the technique of dual-colour CISH using HER-2/neu and chromosome 17 centromere probes in 27 cytological smears, and these cytological samples were obtained from scrapings of fresh breast tumours. We also investigated HER-2/neu amplification and protein overexpression in the corresponding surgical tissues by CISH and IHC using the monoclonal antibody CB11. Of the 27 cytological cases, HER-2/neu gene amplification was observed in nine cases that were positive cases (2+ and 3+) for IHC. Among the 13 IHC positive cases (2+ and 3+), four of them showed no gene amplification. Identical results for the CISH technique were obtained in the matched surgical samples. The scrape samples from fresh breast tumour offer a monolayer cell population that is especially suitable for CISH. This study has shown that the cytological smear might be a good alternative for the CISH test.

Long-term stress and Helicobacter pylori infection independently induce gastric mucosal lesions in C57BL/6 mice.

BACKGROUND: Long-term psychological stresses may have a role in the pathogenesis of peptic ulcer. However, the interaction between stress and Helicobacter pylori infection in the development of peptic ulcer is not established. The aim of this study was to elucidate the roles of long-term stress and H. pylori infection in the development of gastric mucosal lesions in mice. METHODS: The Sydney strain (SS1) of H. pylori was inoculated into the stomach of C57BL/J6 mice. Twelve weeks later, mice with or without H. pylori infection were exposed to long-term repeated water-immersion-restraint stress (WIRS) for 12 h per day, 3 times per week, for 8 weeks. Gastric mucosal lesions were evaluated both macroscopically (ulcer index) and microscopically (Updated Sydney System). RESULTS: The long-term WIRS induced mild inflammation, oedema, interstitial haemorrhage and superficial erosions in the stomach of mice both with and without H. pylori infection. The degree of mucosal inflammation or atrophy in H. pylori-infected mice was not influenced by the stress. In the mice without H. pylori infection, the ulcer index of the stressed mice was greater than that of non-stressed mice (1.66 +/- 0.39 versus 0.17 +/- 0.08, P = 0.007). In the mice with H. pylori infection, the ulcer index (mean +/- s(x)) of the stressed mice was also greater than that of non-stressed mice (2.31 +/- 0.59 versus 0.64 +/- 0.22, P = 0.027). CONCLUSIONS: The present study showed that long-term stress can induce gastric mucosal inflammation and erosions, and this effect may occur independently of H. pylori infection.

Risk factors suggesting malignant transformation of gastric adenoma: univariate and multivariate analysis.

BACKGROUND AND STUDY AIMS: Since gastric adenomas are precancerous lesions, polypectomy is necessary. However, there have been no reports suggesting factors capable of predicting malignant transformation of gastric adenomas removed by endoscopic snare polypectomy (ESP) or endoscopic mucosal resection (EMR) in Korea, a country in which gastric cancer is a major problem. The aim of this paper was to elucidate the risk factors suggesting malignant transformation of gastric adenomas removed by ESP or EMR at our center. PATIENTS AND METHODS: Between November 1994 and June 1999, 118 gastric adenomas diagnosed on the basis of endoscopy and histological examinations of the forceps biopsy specimens obtained were treated by ESP or EMR at our department. Factors capable of predicting malignancy were searched for in the endoscopy reports, still photographs, and histopathological findings. RESULTS: Eight of the 118 adenomas ultimately proved to have malignant foci. In the univariate analysis, four of the variables studied--location, histological type, surface redness, and degree of dysplasia--had a statistically significant relationship with malignant transformation. In the multivariate analysis, only the degree of dysplasia had a statistically significant relationship with malignant transformation. CONCLUSIONS: These results suggest that a diagnosis of high-grade dysplasia in forceps biopsy material should be considered an absolute indication for ESP or EMR.

Fine needle aspiration cytology of sclerosing adenosis of the breast.

OBJECTIVE: To analyze the cytologic findings of sclerosing adenosis of the breast. STUDY DESIGN: We reviewed the fine needle aspiration (FNA) cytologic slides of 7 cases of sclerosing adenosis of the breast and compared the cytologic findings with those of 10 cases of fibroadenoma and 7 cases of fibrocystic change. RESULTS: The smears of sclerosing adenosis were moderately to markedly cellular, consisting of small to large groups of benign epithelial cells arranged with variable architecture. Acinar sheets, scattered individual epithelial cells and small, dense, hyalinized stroma were found in all cases of sclerosing adenosis. Epithelial cells in sclerosing adenosis appeared more frequently as acinar sheets and discohesive individual cells than did those of fibroadenoma (P < .05). However, the branching pattern of epithelial sheets, large sheets and bipolar, naked nuclei were commonly found in fibroadenoma (P < .05). Fibroadenoma had large, hypocellular, fibromyxoid stroma, whereas sclerosing adenosis had small, dense, hyalinized stroma occasionally attached to the epithelial sheets. As compared with fibrocystic change, sclerosing adenosis had similar findings but showed more abundant cellularity, acinar sheets and individual epithelial cells, and the presence of stroma (P < .05). CONCLUSION: Findings of frequent acinar sheets and small, dense, hyalinized stroma attached to epithelial sheets can aid the FNA cytologic diagnosis of sclerosing adenosis. Awareness of the presence of scattered individual epithelial cells in cytologic smears of sclerosing adenosis can help prevent a misdiagnosis of malignancy.

Significance of high-risk human papillomavirus detection by polymerase chain reaction in primary cervical cancer screening.

The purposes of this study were to evaluate the incidence of high-risk human papillomavirus (HPV) infection by polymerase chain reaction (PCR) and to assess its diagnostic usefulness in primary cervical screening. PCR testing for HPV type 16, 18, 31 and 33 was performed on 1305 specimens obtained during routine cervical cancer screening. We analysed the concurrent cervical smears and biopsy, and correlated them with the HPV infection status. We also evaluated histologically-proven cases with ASCUS smears according to HPV infection. HPV DNA was identified in eight (0.7%) of 1144 cytologically normal patients; nine (10.5%) of 86 ASCUS; seven (25.0%) of 28 LSIL; 26 (78.8%) of 33 HSIL; and in all of three squamous cell carcinomas (SCC). HPV positivity was significantly associated with cytohistological diagnosis for HSIL of more. In addition, HPV-positive ASCUS cases were found to be associated with histological abnormality rather than HPV-negative. The results indicate that high-risk HPV testing by PCR could be a useful adjunct tool for Pap smear in primary cervical screening. The combination of Pap smear and high-risk HPV testing by PCR might reduce unnecessary colposcopy-guided biopsy of women with cytological diagnosis of ASCUS.

Radiologic spectrum of intraductal papillary mucinous tumor of the pancreas.

"Intraductal papillary mucinous tumor" is now the preferred term to describe a spectrum of proliferation of the pancreatic ductal epithelium. The tumor produces an excessive amount of mucin and results in progressive dilation of the main pancreatic duct or cystic dilation of the branch ducts, depending on the location of the tumor. This tumor is small and localized in a segment of the main pancreatic duct or in branch ducts, particularly in the branch ducts of the uncinate process, but it may also be diffuse, involving a wide area of the pancreatic ducts. Excessive mucin may impede the pancreatic duct flow and, in turn, produce symptoms of chronic pancreatitis. The following findings are seen on imaging studies: lobulated multicystic dilatation of the branch ducts, diffuse dilatation of the main pancreatic duct, intraductal papillary tumors, elongated or globlike mucous plugs in the dilated ducts, and bulging of the papilla into the duodenal lumen. The diagnosis is suggested at ultrasonography, computed tomography, or magnetic resonance cholangiopancreatography. Endoscopic retrograde cholangiopancreatography is the imaging modality of choice for the diagnosis, because it depicts the communication between the cystically dilated branch ducts and the diffusely dilated main pancreatic duct, as well as intraductal papillary tumor and mucous plugs.

Expression of p21Waf1, p27Kip1 and cyclin D1 proteins in breast ductal carcinoma in situ: Relation with clinicopathologic characteristics and with p53 expression and estrogen receptor status.

p21Waf1 (p21), p27Kip1 (p27) and cyclin D1 have recently been reported as useful prognostic markers for patients with breast carcinoma. However, studies on these cell cycle regulators in ductal carcinoma in situ (DCIS) have been extremely limited. Therefore, we studied the immunohistochemical expression of p21, p27 and cyclin D1 proteins in 49 DCIS cases and compared the findings with the clinicopathologic parameters (age, tumor size, gross type, histologic type, histologic grade, necrosis and mitotic index), p53 and estrogen receptor (ER) status. A significant correlation was found between positive p21 immunoreactivity (67.3% of the cases) and well-differentiated histologic grade, non-comedo type, ER-positive and p53-negative (p53-) status. DCIS with p21+/p53- is likely to be the non-comedo type. The overexpression of cyclin D1 (59.2% of the cases) correlated positively with the ER expression (P = 0.001). The p27 protein expression (46.9% of the cases) correlated with the cyclin D1 immunopositivity (P = 0.0003) and ER expression (P = 0.005). No significant associations were seen in the p27 or cyclin D1 expression and other clinicopathologic parameters. Our results suggest that p21 might be more related to the useful biologic markers in DCIS than p27 or cyclin D1. The significant positive association between p21, p27 or cyclin D1 and ER status, and close association of p27 and cyclin D1 expression might be implicated in the tumor biology of DCIS.

A case of primary adenosquamous carcinoma of the liver presented with liver abscess.

Primary adenosquamous carcinoma of the liver is a very rare type of cholangiocarcinoma and is defined as a cancer containing both squamous and adenomatous components in the same lesion. Recently, we experienced a primary adenosquamous carcinoma of the liver presented as liver abscess. A 63-year-old man was presented with a 4-day history of fever and chill. The radiologic study showed a 4 cm-sized, central hypoattenuated mass with peripheral rim enhancement in the left lobe of the liver. Ultrasonography-guided aspiration and biopsy suggested an adenocarcinoma with abscess in the liver. At laparotomy, the tumor occupied the left lobe of the liver and invaded the right diaphragm. An extended left lobectomy and a partial excision of the involved diaphragm were done. Grossly, the tumor was 6 x 5 x 5 cm in size and had an eccentric necrosis. Microscopically, the tumor was composed of adenocarcinoma and squamous cell carcinoma with a transitional area.

Expression of CD34, bcl-2, and kit in inflammatory fibroid polyps of the gastrointestinal tract.

The histogenesis of inflammatory fibroid polyps (IFP) of the gastrointestinal tract, focused on the cell of origin of the stromal cells, is a controversial subject. The reported CD34 reactivity in gastric IFP has implied a histogenetic relationship with a variety of CD34-reactive tumors, including gastrointestinal stromal tumors (GIST). In addition to bcl-2, the majority of GIST has expressed Kit, suggesting an origin in interstitial cells of Cajal (ICC), which are selectively localized around nerve plexuses. Gastric (12) and colonic (two) IFP from 13 patients were studied, using antibodies against CD34, bcl-2, and Kit. IFP expanded muscularis mucosae with prominent vascular channels, inflammatory infiltrates, proliferating stromal cells, and extracellular matrix material. Eleven gastric IFP exhibited concentric stromal proliferations (CP), particularly, around vessels, glands, and muscle bundles. Their stromal cells were CD34 reactive, bcl-2 nonreactive, and Kit nonreactive and showed fibroblast-like appearances with thin, long cytoplasmic processes. In contrast, one gastric and two colonic IFP showed no CP, and their stromal cells were CD34 nonreactive, bcl-2 nonreactive, and Kit nonreactive. IFP with CP may have a different histogenesis from IFP without CP. IFP with CP may originate from a subpopulation of dendritic interstitial cells other than ICC, predominantly localized around blood vessels and muscle fibers in muscularis mucosae of the stomach.

Micropapillary variant of transitional cell carcinoma of the ureter.

Micropapillary variant of transitional cell carcinoma (TCC) is a rare entity, having a distinct micropapillary component mimicking papillary serous carcinoma of the ovary and has been reported exclusively in the urinary bladder. We experienced a case of micropapillary variant of TCC in the ureter. The tumor showed a predominant proportion of micropapillary component and accompanied a TCC in situ lesion and a high-grade TCC. A metastatic lesion in the regional lymph node also showed an entirely micropapillary pattern. Initially, our case was confused with adenocarcinoma, especially metastatic, because the micropapillary architecture resembled an abortive glandular structure and tumor cell nests were predominantly located in empty spaces mimicking vascular invasion. The patient died with peritoneal metastases 20 months after the initial diagnosis. We report the first case of a micropapillary variant of TCC occurring in the ureter.

Aspiration cytology of ectopic cervical thymoma mimicking a thyroid mass. A case report.

BACKGROUND: Ectopic cervical thymoma, first described in 1941 by Boman, is an uncommon tumor of the neck displaying the same histologic features as mediastinal thymoma. Since it is commonly located in the anterolateral part of the neck or is subjacent to or inside the lower pole of the thyroid, the mass is often confused as being of thyroid origin. CASE: A 68-year-old female presented with dyspnea and an anterior neck mass found on routine chest roentgenography. The thyroid scan showed a cold nodule in the lower pole of the left part of the thyroid. Fine needle aspiration (FNA) cytology revealed large numbers of small lymphocytes with hyperchromatic nuclei and frequent clumping pattern in the pale, eosinophilic, fluid background. A few clusters of epithelial cells without atypism were interpreted as thyroid follicular cells. The overall cytologic features were misinterpreted as malignant lymphoma of the thyroid. However, the histologic diagnosis was thymoma, predominantly cortical type. CONCLUSION: The ectopic cervical thymoma is sometimes misdiagnosed as Hashimoto's thyroiditis, anaplastic carcinoma and malignant lymphoma of thyroid on FNA cytology or frozen diagnosis due to its rarity. Therefore, the differential diagnosis of a neck mass showing a variable composition of lymphocyte and epithelial component in a pale, eosinophilic, fluid background should also include ectopic cervical thymoma, especially in elderly females.