Diagnosis Of Adenoid Cystic Carcinoma Research Articles

Adenoid Cystic Carcinoma Arising from the Lower Eyelid

Primary cutaneous adenoid cystic carcinoma is one of the rarest eyelid tumors. A 39-year-old man presented with a small subcutaneous induration in his left lower eyelid close to the lower lacrimal punctum. Under a clinical diagnosis of chalazion, the eyelid induration was extracted surgically via the palpebral conjunctiva. Histopathological examination of the extracted tumor revealed proliferation of basaloid cells with a prominent cribriform pattern containing Alcian blue-positive and periodic acid Schiff-positive material, leading to a diagnosis of adenoid cystic carcinoma. The patient subsequently underwent extended radical excision including the lacrimal sac. No recurrence was observed during 20 months after surgery. Adenoid cystic carcinoma should be considered as a differential diagnosis of eyelid tumors simulating chalazion. Adenoid cystic carcinoma in the eyelid may have a more favorable prognosis than that in the lacrimal gland.

Application of α-smooth muscle actin and c-kit in the differential diagnosis of adenoid cystic carcinoma from polymorphous low-grade adenocarcinoma

The expression of vimentin, alpha-smooth muscle actin (alpha-SMA) and c-kit in adenoid cystic carcinomas (AdCCs) and polymorphous low-grade adenocarcinomas (PLGAs) was investigated immunohistochemically to evaluate the application of these markers to distinguish AdCCs from PLGAs when the histological features are equivocal. Tissue specimens of AdCCs and of PLGAs, formalin-fixed and paraffin-embedded were retrospectively studied using vimentin, alpha-SMA and c-kit. Positive staining for alpha-SMA was identified in all AdCCs and 25% of PLGAs. The immunoreactivity of c-kit in all positive cases of AdCCs (83%) and PLGAs (41%) was more than 50% and less than 50% of tumor cells respectively. The expression pattern for both alpha-SMA and c-kit, in tubular structures of AdCCs was different of that seen in the same structures in PLGAs. The results of this study support the potential application of alpha-SMA and c-kit as an adjunctive aid in the differential diagnosis of AdCCs from PLGAs.

Central adenoid cystic carcinoma of the mandible: Case report and literature review of 16 cases

Central intraosseous adenoid cystic carcinoma (ACC) of the mandible, formerly known as cylindroma, is a rare neoplasm with only 16 cases reported in the literature. We describe the diagnosis, etiology, and treatment of a central ACC located in the mandibular premolar region. We also review the literature. This case illustrates 2 key facts regarding the diagnosis and etiology of ACC. First, central salivary gland tumors should be considered in the differential diagnosis of cystic lytic lesions in the mandible. Second, even though the origin of this type of tumor is still unknown, the presence of ectopic tissue anterior to the submandibular gland in the submandibular area indicates that this tumor might be made up of ectopic embryogenic inclusions.

Immunophenotypic overlap between adenoid cystic carcinoma and collagenous spherulosis of the breast: potential diagnostic pitfalls using myoepithelial markers

Adenoid cystic carcinoma of the breast is a rare neoplasm whose cribriform architecture may mimic invasive cribriform carcinoma, cribriform ductal carcinoma in situ, and collagenous spherulosis. The diagnosis may be even more challenging in needle core biopsies. Immunohistochemical expression of p63 and c-kit distinguishes adenoid cystic carcinoma from invasive cribriform carcinoma and ductal carcinoma in situ. A formal comparison of the immunophenotype of adenoid cystic carcinoma to collagenous spherulosis has not been reported. Of concern is the overlap in myoepithelial markers between these two entities. Both may express S100, smooth muscle actin, and p63. This overlap may cause diagnostic confusion yet is under-emphasized in the literature. The expression profile of newer myoepithelial markers has not been studied in this setting. We evaluated smooth muscle actin, p63, calponin, smooth muscle myosin heavy chain, as well as c-kit, in nine cases of cribriform pattern adenoid cystic carcinoma of the breast in comparison to 12 cases of collagenous spherulosis. Both entities strongly expressed p63 and smooth muscle actin; in adenoid cystic carcinoma, the basaloid myoepithelial-like tumor cells expressed these markers, but the ductular epithelial cells did not. Neither calponin nor smooth muscle myosin heavy chain was expressed in adenoid cystic carcinoma but both were strongly expressed in collagenous spherulosis. Whereas the ductular epithelial cells of adenoid cystic carcinoma were positive for c-kit in all cases, collagenous spherulosis was negative for c-kit. Positive p63 expression by a cribriform breast lesion is not sufficiently specific to confirm a diagnosis of adenoid cystic carcinoma. A broader panel that includes calponin or smooth muscle myosin heavy chain and c-kit is required to exclude collagenous spherulosis in settings in which the distinctive morphologic features that separate these entities are not conspicuously present. Reliance on p63 or smooth muscle actin alone poses a potential diagnostic pitfall in evaluating cribriform breast lesions.

Distinguishing adenoid cystic carcinoma from cylindromatous adenomas in salivary fine-needle aspirates: The cytologic clues and their ultrastructural basis

The utilization of fine-needle aspiration (FNA) biopsy in salivary tumors is hindered by the reluctance of many cytopathologists to report adenoid cystic carcinoma (ACC) because its cylindromatous stroma is observed occasionally in pleomorphic adenoma (PA) and basal cell adenoma (BA), and a diagnosis of ACC results in radical surgery. The aim of this study is to identify dependable features to distinguish the look-alike entities and illustrate their ultrastructural base. We compared 20 cases of ACC to 15 cases of cylindromatous PA and 9 cases of BA. All were direct smears stained with Diff-Quik, hematoxylin and eosin, Papanicolaou, or Ultrafast Papanicolaou (UFP) stain. In addition to the presence of cylindromatous pattern, the amount of cytoplasm in the neoplastic cells and nuclear features were compared. Tissue was dissected from paraffin blocks and processed for electron microscopy in selected cases. The difference in nuclear features can be distinguished in UFP-stained smears and electron microscopy. The nuclei of ACCs were heterochromatic with coarse chromatin and irregular nucleoli, whereas the nuclei of PAs were euchromatic with fine chromatin and small compact nucleoli. The nuclei of BAs were hyperchromatic but finely textured. The cytoplasm of PAs was detectable with every stain at 40x objective, but the cytoplasm of BAs required UFP stain and 100x objective to be detected. The cytoplasm of majority of neoplastic cells of ACCs are invisible, because the thin rim of cytoplasm measured <1 microm ultrastructurally, well beyond the resolution of a light microscope. Rare cohesive fragment of epithelial cells in ACC have scanty blue cytoplasm in UFP stain and can be recognized as ductal cells. In conclusion, in our analysis of salivary tumors with a cylindromatous pattern, the seemingly naked nuclei of neoplastic cells with their coarse nuclear chromatin and irregular nucleoli, as revealed by the UFP stain, reliably distinguished ACC from cylindromatous adenomas.

Immunoreactivity for c-kit and p63 as an adjunct in the diagnosis of adenoid cystic carcinoma of the breast

Adenoid cystic carcinoma of the breast represents a unique clinicopathologic entity with a variable histological appearance and a relatively indolent clinical course in most of the cases. Adenoid cystic carcinoma may be difficult to differentiate from infiltrating duct carcinomas, and in particular from tubular and cribriform carcinomas, especially in core or vacuum-assisted biopsies. We evaluated the prevalence of c-kit, p63, and e-cadherin immunoreactivity in a series of 20 adenoid cystic carcinomas, comparing the results with those obtained in a series of infiltrating tubular carcinomas and infiltrating cribriform carcinomas. The hormone receptor status, proliferation labeling index, and HER/2 immunoreactivity had been previously investigated in all the cases. Three (15%) adenoid cystic carcinomas and all infiltrating tubular and cribriform carcinomas showed estrogen receptor and/or progesterone receptor immunoreactivity (P<0.00001 for estrogen and P=0.00002 for progesterone receptors). Adenoid cystic carcinomas consistently lacked any immunoreactivity for HER/2, whereas three (15%) infiltrating and cribriform carcinomas showed weak and incomplete membrane staining (P=0.23077). Membranous immunoreactivity for c-kit was found in all except one (predominantly basaloid) adenoid cystic carcinomas (95%), and in none of the infiltrating tubular and cribriform carcinomas (P<0.00001). Nuclear immunoreactivity for p63 was found in all except three (predominantly basaloid) adenoid cystic carcinomas (85%) and in none of the infiltrating tubular and cribriform carcinomas (P<0.00001). All infiltrating tubular and cribriform carcinomas and 18/20 (90%) adenoid cystic carcinomas showed immunoreactivity for e-cadherin (P=0.48718). In summary, adenoid cystic carcinomas showed the following phenotype: estrogen receptor−/progesterone receptor−/c-kit+/p63+ (13 cases, 65%), estrogen receptor−/progesterone receptor/c-kit+/p63− (three cases, 15%), estrogen receptor−/progesterone receptor−/c-kit−/p63+ (one case, 5%), estrogen receptor+/progesterone receptor+/c-kit+/p63+ (two cases, 10%), and estrogen receptor+/progesterone receptor−/c-kit+/p63+ (one case). By contrast, all the infiltrating tubular and cribriform carcinomas showed the estrogen receptor+/progesterone receptor+/c-kit−/p63− phenotype. Our data provide evidence that immunoreactivity for c-kit and/or p63 may be useful in differentiating adenoid cystic carcinomas from other types of breast cancer.

Adenoid Cystic Carcinoma of the Salivary Glands: A 20-year Review with Long-Term Follow-Up

The behavior of adenoid cystic carcinoma (ACC) of the salivary glands has been shown to be unpredictable in terms of local and distant spread and mortality. We retrospectively studied 35 operations in 34 patients who had had a pathologic diagnosis of ACC of the salivary glands and who had been treated over a 20-year period and followed for a minimum of 10 years. We analyzed the effect that different factors had on outcomes. The site of origin appeared to be an important factor in survival rates; survival among patients with tumors that had originated in the parotid gland was fairly good, while survival among those with tumors that originated in the minor salivary glands was significantly worse. TNM staging was another significant factor in survival. Other poor prognostic indicators were local spread, nodal positivity, distant metastasis, and local and regional recurrence. Radiation and chemotherapy did not appear to be beneficial for patients with advanced disease. We recommend radical surgery with complete resection for all patients with ACC of the salivary glands and a careful assessment of the neck in patients with minor salivary gland tumors.

Detection of C-KIT (CD117) molecule in benign and malignant salivary gland tumours

C-KIT (CD117), a tyrosine kinase receptor, is involved in the growth and development of normal tissues and some types of neoplasms. In the present study we analysed the expression of this molecule in salivary gland tumours. Archival formalin-fixed, paraffin-embedded sections of 40 benign and 57 malignant salivary gland tumours were retrieved and retrospectively studied immunohistochemically using a polyclonal C-KIT antibody in an Envision/HRP technique. In addition five samples of chronic submandibular sialadenitis, five normal minor salivary glands and parotid or submandibular gland tissue adjacent to benign tumour were also studied. C-KIT expression was observed in cases of adenoid cystic, acinic cell polymorphous low grade, epithelial-myoepithelial, carcinosarcoma and basal cell adenocarcinomas, as in luminal cells of pleomorphic adenomas, in serous acinar and only in intercalated and a small number of striated ductal cells of inflammatory salivary gland tissue, whereas normal salivary lobules were generally negative except a weak positivity of intercalated cells. Contrary to other reports, this study suggests that, C-KIT protein does not appear to be an exclusively specific marker for benign or malignant salivary gland neoplasms, but may be useful in differential diagnosis of adenoid cystic carcinoma from polymorphous low grade adenocarcinoma. Furthermore its expression in serous acinar cells in sialadenitis and intercalated ductal cells in normal and inflammatory lesions may indicate a possible participation in pathogenesis of both neoplastic and non-neoplastic salivary gland diseases.

Retraction halos in adenoid cystic carcinoma

Fine-needle aspiration (FNA) is an extremely useful diagnostic modality in the evaluation of head and neck masses, including salivary gland neoplasm, contributing to effective patient management. Adenoid cystic carcinoma (ACC) is a primary salivary gland neoplasm with characteristic cytomorphological features including the presence of tightly cohesive fragments of basaloid cells arranged around spheres of hyaline material. Histopathological patterns of growth include cribriform, solid, and tubular architecture. ACC is one of the most common primary malignant tumors, accounting for about 30% of all salivary gland cancers. A great proportion of ACC cases display perineural invasion. Surgery is the treatment of choice. ACCs are highly invasive with early regional and systemic metastasis. Recurrence is common and may occur many years after the primary occurrence. Here, we report an unusual cytomorphological appearance in a case of ACC. The patient was a 26-yr-old otherwise healthy woman who noticed a “lump” in the right submandibular gland area, 2–3 mo before presentation. Bimanual palpation revealed an approximately 1.5to 2-cm irregular, firm nodular region within the substance of the right submandibular gland. Inspection of the rest of the neck demonstrated no obvious lymphadenopathy. A review of CT scan showed a 1to 1.5-cm hyperlucency in the right submandibular gland. An FNA of the submandibular mass was performed. Cytopathological examination of the aspirate revealed abundant blood with interspersed round globular structures without any associated cellular material. The eye-catching feature of these structures was the presence of large clear zones surrounding each globule or the “retraction halos” (RH) as observed on Papanicolaou-stained smears. Higher magnification revealed the amorphous nature of these somewhat basophilic globules, with suggestion of concentric lamellations (Fig. C-1). A closer examination did reveal occasional small basaloid cells scattered in the background appearing mostly as naked nuclei. These nuclei were round to oval and monomorphic and were only rarely seen in proximity to the hyaline globules. A diagnosis of ACC was rendered in this case, although reservations were expressed in the cytological report because of a relative lack of cellular material. Several other entities were entertained in the differential diagnoses, such as mucoepidermoid carcinoma because the globular material did appear to have a mucinous quality. However, no evidence of either glandular or squamous component was observed. The similarity of the globular structures to the concentrically lamellated psammoma bodies raised the possibility of an occult thyroid papillary carcinoma. The clinical presentation was unusual for this scenario. After the FNA diagnosis, the patient underwent resection of the submandibular mass, which did reveal an ACC. RHs are an artifact of smear preparation and fixation. RHs result from shrinkage of the cellular or matrix material, which leaves a circumferential zone of clear space not occupied by other cells or cellular products. This phenomenon has been observed frequently in malignant mesothelioma as observed in serous effusion samples. The RHs are created in alcohol-fixed smears and are seldom observed in air-dried material. The authors have not seen RHs in ACC, particularly in a setting where they are exclusively associated with the hyaline globules. A diagnosis of ACC was rendered in this case despite the relative paucity of the epithelial component. However, this was after careful exclusion of all other diagnostic possibilities. The case described here highlights an unusual phenotypic appearance of ACC, which should be kept in mind when evaluating a salivary gland lesion on FNA. To the best of our knowledge, this peculiar cytomorphology has never been described before in ACC. Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland *Correspondence to: Syed Z. Ali, M.D., Department of Pathology, The Johns Hopkins Hospital, PATH 406, 600 N. Wolfe St., Baltimore, MD, 21287. E-mail: sali@jhmi.edu Received 1 July 2004; Accepted 7 September 2004 DOI 10.1002/dc.20195 Published online in Wiley InterScience (www.interscience.wiley.com).

New Criteria for Cytologic Diagnosis of Adenoid Cystic Carcinoma

To formulate new criteria for adenoid cystic carcinoma (ADCC).The usefulness of 17 items for a cytologically definitive diagnosis of ADCC was examined. The frequency (- - +++) of the 17 items in 18 cases of ADCC and 10 non-ADCC cases (pleomorphic adenoma, basal cell adenoma, myoepithelioma and epithelial-myoepithelial carcinoma) that displayed mimicking cytology was examined cytologically. The total score for cases of ADCC was compared with that for non-ADCC cases.The 17 items included broad intercellular spaces with adhesion; green, granular/cobwebby cytoplasm with translucent intercellular matrix with Papanicolaou staining; coarse hyperchromatin with little nuclear clearing; indistinct and partially distinct nucleoli; small nuclei; broad, smooth margin (SM) space; and translucent M/HG/SM. All cases with a total score of > 21 were ADCC (93.8%). All cases with a total score of < 12 were non-ADCC (87.5%).The 17 items appear to be useful as new criteria for ADCC.

Cytologic diagnosis of adenoid cystic carcinoma of parotid

Cytologic diagnosis of adenoid cystic carcinoma of parotid

Extracellular Hyaline Material in Association with Other Cytologic Features in Aspirates from Collagenous Spherulosis and Adenoid Cystic Carcinoma of the Breast

To reevaluate breast aspirates showing extracellular hyaline material (EHM) and globules to assess if clinicoradiologic and cytologic features could help in differentiating between benign and malignant lesions, especially collagenous spherulosis (CS) and adenoid cystic carcinoma (ACC). Fine needle aspiration was performed on 884 patients with breast lumps. The cytomorphologic features of 6 cases showing EHM, including classic hyaline globules (HGs), were analyzed in detail. Three cases also had hemorrhagic nipple discharge. Tissue diagnosis (4) and mammography (6) were available. Aspirate smears revealed high cellularity composed of monolayers: clusters of uniform, small cells; EHM; and HGs surrounded by similar cells. Benign naked nuclei and stromal fragments (4), nuclear pleomorphism (3), apocrine cells (2), foam cells (2), naked HGs (2) and spindle cells in proximity to HGs were also seen (4). Nipple discharge smears showed foam cells, erythrocytes (3) and epithelial cell clusters with hyaline material (1). The cytologic diagnosis was CS (4) and ACC (2). Histopathology confirmed the diagnosis of CS (2) and ACC (1). There may be a morphologic overlap between the cytomorphologic features of CS and ACC, leading to diagnostic errors. The presence of EHM and HGs in association with bland cellular features should be interpreted with caution to avoid erroneous diagnoses. Histopathology is mandatory in these cases because of their different prognostic implications.

Diagnostic and therapeutic approach to sialoblastoma: Report of a case

The natural history of a rare parotid tumor, the sialoblastoma (embryoma) is reported. It is a blastematous neoplasm said to recapitulate the epithelial differentiation of a gland at various stages of development. The tumor grew in a period of 5 years (from shortly after birth until it was excised) to a firm asymptomatic mass measuring 5 cm in greatest diameter. With a diagnosis of adenoid cystic carcinoma (a common misdiagnosis), the patient was referred to the reporting institution, where the diagnosis was revised. Five months later, completion parotidectomy for presumed recurrence failed to demonstrate residual tumor. One year later, the patient appears to be free of disease. The authors propose that sialoblastomas should be regarded neither as benign nor malignant, but as one single disease with local infiltrative potential. Based on this concept, sialobiastomas can be treated with early conservative surgery alone, provided that free margins are obtained.

Adenoid cystic carcinoma of the breast: a tumour commonly devoid of oestrogen receptors and related proteins.

Adenoid cystic carcinoma (ACC) of the breast is an uncommon well-differentiated tumour with good prognosis, and sometimes difficult to distinguish from in-situ and invasive cribriform carcinoma (ICC) which are relatively more common. Recently, we encountered a case of ACC that proved to be totally oestrogen receptor (ER) negative by immunohistochemistry. We investigated the possibility that this may be a consistent feature that can help in differentiating ACC from ICC which are usually ER positive. The immunoperoxidase technique was used to study the expression of ER and other related proteins in six cases of ACC and two cases of ICC. All ACC cases were negative for oestrogen (ER) and progesterone (PgR) receptors whereas the two ICC were strongly positive for ER and showed a variable degree of PgR positivity. In addition, ACC cases were pS2 negative and showed minimal expression of prolactin receptors (PrlR), while the two ICC showed widespread and strong staining for pS2 and PrlR. The percentages of cells staining positively for Ki67 and p27 were generally lower in ACC than in ICC. Both tumour types were c-erbB-2 negative, but p53 was weakly to moderately positive. The findings suggest that a negative immunoperoxidase staining for ER would confirm the diagnosis of ACC in contrast to the positive staining which is always seen in ICC. The findings also raise the issue of the presence of a specific class of ER negative breast carcinomas which are negative not because of poor differentiation, but because of their derivation from, or differentiation along, an ER negative cell lineage.

Cytologic diagnosis of adenoid cystic carcinoma of salivary glands.

The cytomorphologic features in fine-needle aspiration (FNA) biopsies from 31 primary and 33 recurrent adenoid cystic carcinomas (ACC) were investigated. The correct FNA diagnosis was established in 24 of 31 primary ACC (77%). The diagnostic clue in aspirates from ACC are large globules of extracellular matrix, partially surrounded by basaloid tumor cells. In FNAs with predominance of basaloid tumor cells, but lacking characteristic globules, all other benign and malignant salivary gland tumors of epithelial-myoepithelial differentiation should be considered in the cytologic diagnosis. Pleomorphic adenoma is most frequently confused with ACC, and therefore, the cytologic findings in FNAs from 50 pleomorphic adenomas were compared with those diagnosed as ACC. Furthermore, rare neoplasms of salivary glands with epithelial-myoepithelial cell differentiation, including basal-cell adenoma and carcinoma, epithelial-myoepithelial carcinoma, and polymorphous low-grade adenocarcinoma, as well as some nonsalivary gland neoplasms presenting an adenoid cystic pattern, must be considered. The cytologic features of these entities are discussed in detail with respect to the cytologic diagnostic criteria of ACC.

Delay in Diagnosis of Adenoid Cystic Carcinoma

denoid cystic carcinoma is a malignant neoplasm that can occur in many head and neck locations including the nasal cavity, paranasal sinuses, lacrimal gland, esophagus, and in both minor and major salivary gland tissue. Understanding this form of adenocarcinoma is especially important because of its growth characteristics, high rate of recurrence,and potential for distant metastasis. Adenoid cystic carcinoma can present as a unilobular mass of the salivary glands. The practicing clinician and pathologist play a dual role in the diagnosis and treatment of this malignancy. Depending on the size and location of the tumor, treatment options can range from limited surgical excision to radical surgery with radiation therapy. Failure to include a malignant neoplasm in the differential diagnosis when confronted with a palatal tumor can lead to delays in treatment Early diagnosis of adenoid cystic carcinoma of the salivary glands is critically important to increased treatment success rates. The purpose of this case discussion is to emphasize features common to intraoral adenoid cystic carcinoma and to highlight the need for early diagnosis and appropriate treatment.

前舌腺原発と思われる腺様嚢胞癌の１例

This report describes a case of adenoid cystic carcinoma (ACC) originating in the anterior portion of the tongue. The patient was a 73-year-old woman who complained of swelling of her tongue and gustatory disturbance. A neoplasm was located in right side of the tongue. A partial glossectomy, right-sided functional neck dissection, and immediate reconstruction using a SMMC flap were performed after diagnosis of ACC of the tongue. Histological examination revealed solid cancer nests intermingled with cribriform areas. It appeared that ACC in this patient originated in the minor salivary gland, perhaps the anterior lingual gland. There has been no evidence of local recurrence or distant metastasis as of 6 years after surgery.

Diagnostic Pitfalls in Aspiration Biopsy Cytology of Papillary Breast Lesions.

Our experience with 12 papillary breast lesions included eight intraductal papillomas, three primary papillary carcinomas, and one metastatic papillary ovarian carcinoma. Five of the eight intraductal papillomas displayed diagnostic findings including tridimensional papillary fragments of ductal cells with distended cytoplasmic vacoules and dense scalloped cytoplasm. Three intraductal papillomas displayed cohesive fragments containing epithelial cells surrounding metachromatic, globoid, and cylindrical structures that were bright red following Diff-Quik staining and pale blue following Papanicolaou staining. Such unusual findings may raise the differential diagnoses of adenoid cystic carcinoma and collagenous spherulosis. However, the metachromatic material of intraductal papilloma represents type-I collagen-rich stroma of hyalinized fibrovascular stalks, while the material of adenoid cystic carcinoma and collagenous spherulosis represents type-IV collagen. Two of the three primary papillary carcinomas displayed cytologic findings similar to those of intraductal papillomas except for increased anisonucleosis and cell dyshesion, while the third displayed innumerable psammoma bodies similar to the metastatic ovarian carcinoma.

Differential Diagnosis of Adenoid Cystic Carcinoma from Pleomorphic Adenoma of the Salivary Gland on Fine Needle Aspiration Cytology

To evaluate the distinguishing morphologic features of pleomorphic adenoma and adenoid cystic carcinoma on fine needle aspiration cytology. A retrospective study was undertaken to compare the cytomorphology of 9 adenoid cystic carcinomas with that of 12 pleomorphic adenomas of the salivary gland among histologically proven cases. The most consistent finding for differentiating adenoid cystic carcinoma from pleomorphic adenoma in our study was the amount of cytoplasm of individual tumor cells. Plasmacytoid appearance is a reliable finding for pleomorphic adenoma, and it enables us to rule out adenoid cystic carcinoma. All 12 cases of pleomorphic adenoma showed tumor cells containing abundant cytoplasm in clusters and isolated cells, with plasma cell-like appearance in 9 cases, especially in isolated cells. In contrast with pleomorphic adenoma, most adenoid cystic carcinomas showed little cytoplasm. Hyaline spherical globules were found in four of nine adenoid cystic carcinomas but were not found in any case of pleomorphic adenoma. It was specific but not sensitive to adenoid cystic carcinoma. Fibrillary chondromyxoid ground substance and a mixture of epithelial cells with stroma were found in two-thirds of the pleomorphic adenomas in our cases. The pattern of cell clusters was helpful to differentiate pleomorphic adenoma from adenoid cystic carcinoma. Large, loose clusters with a spindle cell core suggested pleomorphic adenoma. Small, dense trabeculae with a smooth margin and dense clusters containing clear, round spaces were more suggestive of adenoid cystic carcinoma. Overall cellularity, proportion of isolated cells, orientation of cellular clusters and degree of cellular overlapping gave almost no help in making the distinction between the lesions. A plasmacytoid appearance of individual tumor cells with abundant cytoplasm was a reliable finding in pleomorphic adenoma for differentiating it from adenoid cystic carcinoma. Practically, nuclear features were not enough to distinguish the two lesions in isolated cases.

Primary adenoid cystic carcinoma of the cervical trachea mimicking thyroid tumor: CT evaluation.

Our goal was to describe the CT characteristics of adenoid cystic carcinomas of the trachea mimicking thyroid tumors. Computed tomography of four patients with pathologically proved adenoid cystic carcinomas extending into the thyroid gland was retrospectively reviewed. One case was also examined with MR. The masses encircling the trachea and circumferential thickening of the tracheal wall were demonstrated in all four cases. The longitudinal extent of the tracheal wall thickening was also demonstrated in all cases. The tumors had a broad base on the trachea and convex margin on the thyroid gland. They were all homogeneous, generally smoothly marginated, and isoattenuating on postcontrast CT scans. Adenoid cystic carcinomas were usually seen on CT scans as homogeneous masses encircling the posterolateral trachea with thickening of the tracheal wall in the transverse and longitudinal planes. These CT characteristics may be helpful in the differential diagnosis of adenoid cystic carcinomas mimicking thyroid tumors.