Cytodiagnosis of a primary non-Hodgkin's lymphoma of bone

We report fine-needle aspiration cytology and histologic findings of a primary non-Hodgkin's lymphoma of bone involving the rib and iliac bones. Smears contained abnormal lymphoid cells and abundant lymphoglandular bodies, suggesting a malignant lymphoproliferative disease. However, histologic sections showed nests of tumor cells with extensive cytoplasmic clearing surrounded by sclerosis, thus mimicking a carcinoma. Clinical data, radiographic findings, and cytohistological correlation led to a final diagnosis of primary non-Hodgkin's lymphoma of the bone, confirmed by immunopositive staining for leukocyte common antigen CD45 and B-cell associated antigen CD20. It is concluded that finding numerous lymphoglandular bodies in bone tumor specimens allows an accurate diagnosis of lymphoid tissue. The rarity of bone lymphoma and the misleading histologic features can cause considerable difficulty in diagnosing this entity. The importance of identifying lymphoglandular bodies and the appropriate use of immunochemistry are emphasized. Diagn Cytopathol 1994;11:168–173. © 1994 Wiley-Liss, Inc.     

Immunohistochemical study on differential diagnosis between NPC and malignant lymphoma

Nasopharyngeal carcinoma (NPC) and malignant lymphoma are common malignant tumors which frequently involve nasopharynx and cervical lymph nodes. Sometimes, it is difficult to distinguish poorly-differentiated NPC, especially undifferentiated NPC, from malignant lymphoma. Paraffin sections of 221 cases of poorly differentiated or undifferentiated NPC and malignant lymphomas were analysed by immunohistochemical techniques (IGSS, ABC, double stain, etc.), The immunohistochemical criteria of differential diagnosis between NPC and malignant lymphomas were proposed and with these criteria, 40 cases which were difficult to distinguish between NPC and malignant lymphoma were identified. In comparison with the methods of SPA, PAP, ABC, IGSS, etc., and the probes of Ke, EMA, LCA, Vi, etc. on paraffin sections, IGSS or ABC method and probes of Ke and LCA were considered to be more sensitive.     

Morphologic unity of Paneth cells

Paneth cells occurring in intestinal and extraintestinal sites were studied using various light microscopic techniques, including standard hematoxylineosin (HE)-stained histologic sections; a number of histochemical reactions, including the phosphotungstic acid-hematoxylin (PTAH) method; and immunohistochemical labeling for the presence of lysozyme using the peroxidase-antiperoxidase (PAP) method. Cells, identified on HE as Paneth cells, uniformly stained with PTAH and PAP-lysozyme. Further, all of the cases demonstrating epithelial cell lysozyme showed eosinophilic cytoplasmic granules, typical of Paneth cells, on HE sections. Lysozyme was demonstrated in benign and malignant ovarian tumors, as well as in a variety of ectopic intestinal sites and benign and malignant intestinal tumors, supporting the concept that the elaboration of lysozyme is a nonspecific feature of intestinal-cell differentiation and is not a response to a specific stimulus.     

Lung carcinoma mimicking malignant lymphoma: Report of three cases

Three cases of lung carcinomas with unusual histologic appearances that have received little or no comment in the literature are presented. They were initially confused with malignant lymphoma because of a diffuse proliferation of relatively monotonous cells simulating large-cell immunoblastic lymphoma. In each case, the possibility of malignant lymphoma was excluded with confidence after the immuno-histochemical study (leucocyte common antigen negative and cytokeratins positive), although with conventional microscopy several foci of cohesive groups of tumor cells were observed. The tumors were ranked at the clinical stage II or III when they were initially discovered, but all patients died of disease within 1 year. The present three tumors show an aggressive behavior and could be classified into a peculiar variant of ‘large cell’ carcinoma. It is necessary for surgical pathologists to have an idea of these variants of lung carcinoma in order to avoid erroneous diagnosis.     

Primary Malignant Lymphoma of the Rectum with Diagnostic Problems

We present two similar cases of rectal B-cell lymphoma with diagnostic problems. Grossly, both tumors appeared as a well demarcated polypoid mass with eroded mucosa. In spite of their histologic resemblance to reactive lymphoid hyperplasia, Including the presence of lymph follicles, fibrosis and polyclonal plasma cells, both cases were diagnosed as malignant lymphoma of low-grade malignancy because of the full-thickness involvement of the rectum with diffusely infiltrated small or medium-sized lymphoid cells showing rare mitoses. In one case, clonal proliferation of differentiated B cells was demonstrated by analysis of gene rearrangement. Therapeutic problems related to low-grade malignant lymphoma in the rectum are also discussed. Acta Pathol Jpn 41: 623-628, 1991.     

Cytomorphologic diagnosis of benign and malignant tumors of the blood vessels

The aim of this work was to define the cytomorphologic patterns of the major cytologic forms of benign and malignant tumors of the blood vessels in order to define the criteria of the diagnosis of these tumors. Parallel cytologic investigations of puncture biopsy specimens and of histologic sections, obtained from 186 patients (156 ones with benign and 30 with malignant tumors) were carried out. Puncture biopsy specimens, impressions, and scrapings off the surface of section of the removed tumors were examined; the preparations were stained according to Kryukov-Pappenheim. Analysis of the findings of histologic and cytologic studies has shown that the features of the cytologic patterns of vessel tumor varieties, distinguished by the authors, helped correctly diagnose the benign or malignant nature of the process by examining the puncture biopsy specimens in 89.8% of cases and identify the histologic type in 41.5% of cases. The per cent shares of recognized benign and malignant tumors were similar: 89 and 90%, whereas the number of identified tumor types was higher in malignant cases than in benign ones: 51.8 vs. 39.5%. Therefore cytologic examinations of the vessel tumor puncture biopsy specimens should be an obligatory component in the complex diagnosis before surgical intervention.     

Exfoliative and aspiration cytology of malignant lymphomas

A cytologic diagnosis of malignant lymphoma based on fine-needle aspirates or body fluids can be made in 50% to 75% of cases. The diagnosis is more reliable for intermediate and high-grade lymphomas than for low-grade small lymphocytic or mixed small cell and large cell tumors. The cytologic evaluation is useful in the diagnosis of recurrence of a previously diagnosed lymphoma and in the determination of the stage, cavity involvement, and distinction between metastatic carcinoma and lymphoproliferative disease. The prognosis and to some degree the clinical management of lymphomas are based on the morphologic and often the immunologic classification. This initial diagnosis is best based on histologic, cytologic, and histochemical examination of surgically excised specimens.     

Controversial issues and new discoveries in lung neuroendocrine tumors

Lung neuroendocrine (NE) tumors consist of four histologic subtypes, which are usually classified based on a three-tiered prognostic scheme. They are typical carcinoid (TC) as low-grade malignant tumors, atypical carcinoid (AD) as intermediate-grade malignant tumors, and large cell NE carcinoma (LCNEC) and small cell lung carcinoma (SCLC), both of which are high-grade malignant tumors. This three-tiered classification is based solely on histologic grounds and is a source of controversy especially when dealing with borderline or “gray zone” categories (TC vs. AC, AC vs. LCNEC, LCNEC and SCLC). In this review, controversial issues regarding the histologic classification will be discussed, and an innovative grading system that incorporates Ki-67 labeling index will be described. In addition, the recently discovered molecular alterations involved in TC/AC, as well as pathways involved in high-grade NE carcinomas, will be discussed in order to elucidate the differences in pathogenesis and biology between carcinoid tumors and high-grade NE carcinomas.     

Fluorescence in situ hybridization analysis of chromosome 12p in paraffin-embedded tissue is useful for establishing germ cell origin of metastatic tumors.

The over-representation of chromosome 12p sequences is crucial for the development of invasive testicular germ cell tumors. Testicular cancer patients may have metastatic tumors of diverse histologic types, including adenocarcinoma, undifferentiated carcinoma, sarcoma, or other malignancies that lack features of germ cell tumors. We sought to investigate the possible germ cell origin of such tumors using interphase fluorescence in situ hybridization. In all, 10 metastatic malignant somatic-type tumors from patients with histories of testicular cancer, as well as one malignant somatic-type tumor from a patient with primary mediastinal germ cell tumor were studied and included: adenocarcinoma (five cases), poorly differentiated carcinoma (one), sarcoma (four), and neuroendocrine carcinoma (one). The tumors were analyzed using fluorescence in situ hybridization using 12p spectrum green and 12 centromeric spectrum orange probes in paraffin sections. The patients ranged in age from 27 to 55 years (mean, 43). Colon and lung cancers from patients without germ cell tumors were used as controls. Adequate signals were observed in all tumors. Gain of chromosome 12p was seen in six tumors. None of the control tumors showed 12p amplification. Fluorescence in situ hybridization for 12p amplification in routinely processed surgical specimens is a useful adjuvant diagnostic tool in confirming the germ cell origin of metastatic tumors having the histologic appearance of somatic-type neoplasms.     

Psammoma bodies in fine-needle aspiration cytology of papillary adenocarcinoma of the lung

The fine-needle aspiration (FNA) cytology of two cases of papillary adenocarcinoma of the lung is reported. Both cases showed psammoma bodies and papillary clusters of tumor cells in FNA specimens. Both tumors were resected and confirmed as primary papillary carcinoma of the lung by histologic examination and by clinicopathologic exclusion of the possibility of metastasis from other organs.     

Pathologic observations of the duodenum in 615 consecutive duodenal specimens in a single Japanese hospital: II. malignant lesions

The author investigated histopathology of 615 consecutive duodenal specimens in our pathology laboratory in Japan. A computer review of the duodenal specimens was done. In cases of malignancy, histological slides were reviewed. The duodenal specimens were composed of 567 benign lesions (92%) and 48 malignant lesions (8%). The 48 malignant lesions were composed of 20 cases (42%) of primary adenocarcinoma, 10 cases (21%) of primary adenocarcinoma of ampulla Vater, 4 cases (8%) of primary squamous cell carcinoma, 1 (2%) cases of primary spindle cell carcinoma, 4 (8%) cases of carcinoid tumors, 1 (2%) case of malignant lymphoma, and 8 cases (17%) of secondary carcinoma from the pancreatic carcinoma or bile duct carcinoma. The primary adenocarcinoma (n=20) was composed of well differentiated adenocarcinoma (n=9), papillary adenocarcinoma (n=1), moderately differentiated adenocarcinoma (n=6), and poorly differentiated adenocarcinoma (n=4). The primary adenocarcinoma of the ampulla of Vater (n=10) was composed of well differentiated adenocarcinoma (n=7) and moderately differentiated adenocarcinoma (n=3). The primary squamous cell carcinoma (n=4) showed proliferation of malignant squamous cells with keratinization and intercellular bridges. The spindle cell carcinoma (n=1) consisted of only malignant spindle cells immunohistochemistry positive for various cytokeratins and vimentin. The carcinoid tumor (n=4) was typical carcinoid and showed organoid, trabecular, and ribbon-like arrangements. The carcinoid tumor was immunohistochemically positive for neuroendocrine markers such as CD56, neuron-specific enolase and synaptophysin. The malignant lymphoma (n=1) was diffuse large B-cell lymphoma immunohistochemically positive for CD10, CD20, and CD79α. The secondary carcinoma (n=8) was adenocarcinoma invaded from the pancreatic adenocarcinoma (n=6) and extrahepatic bile duct adenocarcinoma (n=2).     

前列腺非上皮性肿瘤及瘤样病变的病理观察

目的：探讨前列腺非上皮性肿瘤的诊断和鉴别诊断并观察其预后,方法：收集临床及病理资料,应用HE,免疫组织化学LSAB法及电镜等方法,对16例前列腺非上皮性肿瘤的临床和形态特点进行了观察,并进行了随访,结果：16例中诊断前列腺间质结节6例,前列腺恶性分叶状肿瘤1例,前列腺间质肉瘤3例,前列腺平滑肌肉瘤3例,纤维肉瘤1例,前列腺非霍奇金恶性淋巴瘤2例。结论：伴发生前列腺良性增生过去诊断为前列腺平滑肌瘤的病变为前列腺的间质结节,在穿刺的标本中,前列腺叶状囊肉瘤易与前列腺间质肉瘤混淆,前列腺间质肉瘤以无特定结构的小梭形细胞为特点,前列腺平滑肌肉瘤、纤维肉瘤、前列腺非霍奇金恶性淋巴瘤与软组织同类肿瘤的诊断标准相同。前列腺非上皮性恶性肿瘤预后差。     

34betaE12 Cytokeratin Immunodetection in the Differential Diagnosis of Small Cell Tumors of Lung

The group of small cell tumors of the lung includes fine following: (1) small cell carcinoma (SCC) of neuroendocrine (NE) origin, (2) poorly differentiated squamous carcinoma, (3) the rare basaloid (basal cell) carcinomas, and (4) malignant lymphomas, primitive neuroectodermal tumors (PNETs), and rhabdomyosarcomas. The differential diagnosis among these entities carries a heavy therapeutic impact but may be difficult in small biopsy specimens or in cytologic material, especially if necrosis or artifactual alterations are present. The use of additional techniques such as immunostaining for NE markers is not always helpful, since immunoreactive chromogranin A is detectable in only a small percentage of small cell carcinomas. It has recently been reported that in the aerodigestive tract 34betaE12 cytokeratin (CK) immunostaining selectively labels non-NE carcinomas, including squamous cell carcinoma, adenocarcinoma, and the rare basaloid carcinoma. We evaluated the role of such CK immunodetection in the differential diagnosis of small cell lung tumors in cytologic and biopsy specimens. Eighty-one lung tumors diagnosed by means of endoscopic bronchial biopsy, fine needle aspirate, or bronchial washing were collected. They included 43 small cell NE carcinomas and 38 cases used as controls (comprehensive of 2 large cell neuroendocrine carcinomas, 4 carcinoid tumors, 30 cases of non-NE lung carcinomas, 2 cases of bronchial infiltration by non-Hodgkin lymphomas). 34betaE12 CK immunoreactivity was found in 29/30 cases of non-NE carcinomas, but in only 3/43 SCCs. The latter showed positivity in only a few scattered cells. The 2 cases of bronchial infiltration by malignant lymphoma as well as the 4 cases of carcinoid tumors and the 2 cases of large cell neuroendocrine carcinomas were negative. These findings were confirmed in the surgical specimens of operatedon cases. We conclude that, in lung carcinoma biopsies showing a small cell pattern, presence of 34betaE12 CK immunoreactivity favors a non-NE carcinoma, whereas its absence supports the diagnosis of SCC. Int J Surg Pathol 8(4):317-322, 2000     

原发性心脏恶性肿瘤9例临床病理分析

目的；分析原发性心脏恶性肿瘤（PCMT）的发病学特点、病理组织类型及形态学基础。方法：应用HE染色，组化及免疫组化标记对9例PCMT进行了形态学观察，并对其临床资料作了分析。结果：根据形态学发现和免疫组化结果，9例PCMI可分为心脏恶性间皮瘤（3例）、血管肉瘤（2例）、B细胞淋巴瘤（2例）、心包胸腺瘤（1例）及交界性上皮样血管内皮瘤（1例）。结论：PCMT和见，多于中年男性，好发于心房，多数恶性肿瘤预后差，肿瘤类型多，形态结构复杂，免疫组化标记对确定肿瘤起源很有帮助，早期发现、准确诊断与局部肿瘤全切除，对肿瘤的治疗和预后分析非常重要。     

恶性颗粒细胞瘤10例临床病理学观察及文献复习

目的 探讨恶性颗粒细胞瘤的临床病理学特征,评价组织学上诊断恶性的标准。方法 对10例恶性颗粒细胞瘤的临床资料和组织学形态进行回顾性分析,并采用免疫组织化学(LSAB法)和电镜检测研究其免疫表型和超微结构。结果男性4例,女性6例,年龄范围为27～73岁(平均46岁)。临床上,9例表现为皮下或深部软组织内无痛性生长的孤立性肿块,其中1例伴有周围神经症状。肿瘤位于下肢3例,乳腺2例,项部2例,胸壁、右颈部和盆腔者各1例。肿瘤直径2～11cm,平均4．8cm。镜下由成巢或成片的多边形细胞组成,胞质呈嗜伊红色颗粒状,与良性性颗粒细胞瘤极为相似,但仔细观察发现,9例显示至少下述形态中的3种：核增大呈空泡状并可见明显的核仁;多形性瘤细胞;核质比增大;瘤细胞趋向梭形;可见核分裂象;凝固性坏死。除经典性形态外,1例尚可见散在的多核性瘤细胞。余1例除局部区域显示核增大呈空泡状并可见明显的核仁外,其余形态均不明显,但临床上却呈恶性经过。9例均强阳性表达S-100蛋白和神经元特异性烯醇化酶(NSE),7例尚表达CD68。电镜观察显示瘤细胞胞质内充满大量退变的复合性溶酶体。随访7例,5例复发,4例转移,2例死于肿瘤。结论 (1)Fangburg-Smith等的组织学恶性标准具有较高的可重复性,但在少数情形下,最终诊断仍需结合肿瘤的生物学行为;(2)提议将核分裂象的标准修订为＞5／50HPF;(3)广泛性局部切除加上必要的区域淋巴结清扫仍是目前最主要的治疗手段,辅助性化疗和(或)放疗并不能明显改善患者的预后;(4)描述一种尚未见报道的多核性瘤细胞形态亚型。     

Diagnostic problems in the subtyping of renal tumors encountered by five pathologists

The diagnostic problems in the subtyping of renal tumors were evaluated by a panel of five pathologists studying a set of selected tumors. Five pathologists independently assessed a single hematoxylin-and-eosin (HE)-stained slide from 28 selected renal tumors. After this independent assessment, the pathologists reevaluated and discussed all discordant cases. Additional HE-stained sections and immunohistochemically (IHC) stained slides were available. The generalized kappa for interobserver agreement was calculated. After independent assessment of the HE-stained slides, the five pathologists unanimously reached an agreement in the decision between malignant and benign in 82% of the cases. Fifty percent of the cases were correctly subclassified. The overall generalized kappa value for the five pathologists was 0.320 (CI 95% 0.090-0.551), which is considered a moderate agreement. A 100% agreement was reached for all 28 cases after examination of more slides from different tumor areas and IHC-stained sections. An accurate histologic distinction between benign and malignant renal tumors is possible on one HE-stained section. Correct assignment of the subtype is difficult on one slide alone and relies on IHC-markers and additional slides. Tumors composed of an eosinophilic cell type and tumors with a papillary growth pattern were the major causes of an incorrect diagnosis on an HE-stained section alone.     

Histopathologic study of the rectum in 1,464 consecutive rectal specimens in a single Japanese hospital: II. malignant lesions

The author investigated histopathology of 1,464 consecutive rectal specimens in of our pathology laboratory in Japan. A review of pathological reports was done by computer. Observation of histological slides was performed, when appropriate. The rectal specimens were composed of 1,041 benign lesions and 423 malignant lesions. The 423 malignant lesions were composed of 367 cases of primary rectal carcinoma, 41 cases of carcinoma in adenoma, 7 cases of neuroendocrine tumor, 3 cases of malignant lymphoma, 2 cases of gastrointestinal stromal tumors (GIST), and 3 cases of metastatic carcinoma. Of the 367 cases of primary rectal carcinoma, 37 cases were early carcinomas whose invasion was limited up to the submucosa (early rectal carcinoma). The remaining 330 cases were advanced carcinoma invading beyond the proper muscle layer. The histological types were well differentiated adenocarcinoma in 197 cases, moderately differentiated adenocarcinoma in 129 cases, poorly differentiated adenocarcinoma in 10 cases, mucinous adenocarcinoma in 24 cases, signet ring cell carcinoma in 6 cases, squamous cell carcinoma in 1 case In the 41 cases of carcinoma in adenoma, the carcinoma was well to moderately differentiated adenocarcinoma, and all cases were early carcinomas without invasion or with little invasions to subserosa. The size of carcinoma in adenoma was as follows: < 10 mm, 5 cases; 10-15 mm, 8 cases; 15-20 mm, 23 cases; > 20mm, 5 cases. The background adenoma was as follows: tubular adenoma (n=15), tubulo-villous adenoma (n=14), and villous adenoma (n=12). The 7 cases of neuroendocrine carcinoma consisted of 6 low grade neuroendocrine tumors (carcinoids) and 1 high grade neuroendocrine carcinoma (small cell carcinoma). All were submucosal lesions. Immunohistochemically, the tumor cells were positive for two or more of synaptophysin, chromogranin, neuron-specific enolase, CD56. In small cell carcinoma, KIT and PDGFRA were consistently positive. The 3 cases of malignant lymphoma were diffuse large B-cell lymphomas positive for CD20 and CD79a and negative for NK/T cell markers. The two cases of GIST was spindle cell type, and the risk was intermediate. Kit mutations were recognized in both GISTs. No PDGFRA mutations were seen. Of the 3 metastatic carcinomas, one was a metastasis from prostatic adenocarcinoma, and the remaining two was adenocarcinoma of unknown primary sites.     

Morphometric studies for objective diagnosis of intraductal carcinoma of the breast.

In order to obtain objective histologic criteria for distinguishing intraductal carcinomas of the breast from benign intraductal hyperplasia, a morphometric study was carried out on 15 cases of breast carcinoma (5 cases of comedo carcinoma, 5 cribriform carcinoma and 5 papillotubular carcinoma) and 10 benign control lesions (5 papilloma and 5 fibrocystic disease). Morphometric analysis was performed for each group with regard to 1) mean nuclear area, 2) mean nucleolar size, 3) mitotic index, and 4) nuclear count within predefined area (nuclear density) in histologic specimens. The results obtained were as follows: 1) Mean nuclear area for comedo carcinoma was distinctively large. This, together with its coefficiency variance, may be a good indicator for identifying this type of carcinoma. 2) Mean nucleolar size was significantly larger in each carcinoma group than in their benign counterparts. Nucleolar size was therefore considered to be the most reliable parameter for discriminating malignant cells from benign hyperplasia. 3) Mitotic index was relatively high in comedo and papillotubular carcinomas. 4) No difference was seen in nuclear density between the malignant and benign groups. In addition to the major criteria, combined application of these morphometric indicators might also be helpful for practical histologic assessment.     

Exfoliative sputum cytology of cancers metastatic to the lung

Although largely replaced by fine-needle aspiration (FNA) and bronchoscopy, cytological examination of sputum for exfoliated malignant cells still is considered a valuable initial diagnostic test in patients presenting with a lung mass. Thirty-five cases of secondary/metastatic tumors involving the lung and diagnosed on sputum were retrospectively reviewed from our cytopathology files for a period of 22 yr (1980-2001). Clinical history and the relevant histopathological material were examined and correlated with the cytological findings. In all cases, a history of malignancy was known. Cytological diagnoses included colonic adenocarcinoma (7 cases); non-Hodgkin's lymphoma (NHL; 5 cases); malignant melanoma (MM; 5 cases); breast carcinoma (5 cases); Hodgkin's lymphoma (HL; 3 cases); pancreatic adenocarcinoma (2 cases); prostatic adenocarcinoma (2 cases); and 1 case each of urothelial carcinoma, endometrial carcinoma, renal cell carcinoma, hepatic small-cell carcinoma, squamous-cell carcinoma (cervix), and leiomyosarcoma (LMS). Cellular preservation was optimal in all cases. The smear background was relatively clean in 25 (71%) cases and predominantly inflamed and/or necrotic in 10 (29%) cases. In non-lymphoid tumors (27 cases), isolated single malignant cells were seen in 7 (26%) cases (all cases of MM and prostatic adenocarcinoma), whereas 20 (74%) cases displayed fragments with intact tumor architecture. Overall, only 10/35 (29%) cases showed noticeable tumor-cell necrosis. In one case (LMS), cell block sections were used for immunoperoxidase (IPOX) studies with positive staining for desmin and actin. Exfoliation of cancer cells in sputum from secondary tumors in the lung is a rare phenomenon in current-day practice, with metastatic colonic adenocarcinoma seen most commonly. Intact tumor architecture was observed in exfoliated cells in 75% of the cases.     

Sclerosing mucoepidermoid carcinoma with eosinophilia of the salivary glands

We encountered two cases of low malignant mucoepidermoid carcinoma with scanty cellular atypism which originated in the parotid or submandibular gland and was characterized by marked fibrosis and eosinophilic infiltration within tumor tissue despite the predominance of the squamous component. Here we report these two cases and provide a review of the literature. We believe that clinically these two tumors with stromal fibrosis and eosinophilic infiltration have a low malignant potential, although histological examination revealed a scanty mucus-producing epithelial component. Therefore, we consider this type of tumor as a new subtype of mucoepidermoid carcinoma. A low-malignant mucoepidermoid carcinoma with stromal fibrosis and eosinophilic infiltration, as described in these two cases, may be misdiagnosed as a highly malignant mucoepidermoid carcinoma or squamous cell carcinoma because of its histologically scanty mucus-producing epithelial component. The objective of this study was to clarify their differences and to discuss the rendering of an accurate histological diagnosis, the degree of malignancy in relation to prognosis prediction, and the choice of therapy. In addition, we propose regarding this type of tumor as a new subtype of mucoepidermoid carcinoma.