Fine-needle aspiration biopsy of a cystic pleomorphic adenoma with extensive adnexa-like differentiation: differential diagnostic pitfall with mucoepidermoid carcinoma

Although fine-needle aspiration biopsy (FNAB) is a highly accurate tool for the diagnosis of pleomorphic adenomas, even this common salivary gland neoplasm can be diagnostically challenging and cause pitfalls in cytodiagnosis. In particular, the presence of either cystic degeneration or squamous and mucinous metaplasia can lead to a false positive diagnosis of malignancy. Here we present the case of a 16-year-old female who presented with a painless, slowly growing mass in the superficial lobe of the right parotid gland. Magnetic resonance imaging of the parotid demonstrated a mass with heterogeneous postcontrast enhancement and a central, nonenhancing area suggestive of necrosis. FNAB of the lesion yielded proteinaceous debris and numerous whorls of keratin, small cohesive clusters of basaloid and squamoid epithelial cells, and many vacuolated and foamy cells. Initially and after consultation at an outside institution, the FNAB was reported as an "atypical neoplasm, cannot exclude mucoepidermoid carcinoma." A total, nerve-sparing parotidectomy and level II neck dissection revealed a pleomorphic adenoma with central cystic degeneration and extensive mixed appendageal differentiation. While foci of squamous metaplastic changes may occur in pleomorphic adenomas, the combination of cystic degeneration and extensive appendageal differentiation with numerous keratotic cysts is rare, and it presents the potential for misinterpretation of the FNAB as indicative of malignancy in general, and mucoepidermoid carcinoma in particular.     

Fine-needle aspiration biopsy of adenoid cystic carcinoma of the breast: A case report

We describe the cytologic findings of a fine-needle aspiration (FNA) breast lesion with a typical histology for adenoid cystic carcinoma. The aspirate yielded highly cellular smears with a monomorphic population of small, slightly atypical cells, arranged in multilayered groups with abundant fine intercellular metachromatic substance between cell groups. There were also fragments of fibrillar stroma in close relation to epithelial cells. The diagnosis based on the FNA material was suspicious of malignancy. The cytomorphology in this case presented a difficult differential diagnosis with pleomorphic adenoma. Features indicative of adenoid cystic carcinoma were nuclear cell hyperchromasia, the presence of small nucleoli, and scant, poorly defined, or absent cytoplasms. Differential diagnosis of breast adenoid cystic carcinoma with other entities will also be discussed. Diagn Cytopathol 1996;15:431–434. © 1996 Wiley-Liss, Inc.     

Ultrastructural similarities of adenoid cystic carcinoma and pleomorphic adenoma

Ultrastructural examination of five adenoid cystic carcinomas, three breast and two salivary gland, reveals identical patterns of tumour cell differentiation, organization and distribution of cellular products (Zaloudek, Oertel & Orenstein 1984). In both sites, there is proliferation of two populations of cells, one with characteristics and organization of duct-type luminal epithelial cells and a second that forms the principal proliferating component and has the overall organization and appearance that would suggest that they represent modified myoepithelial cells. Recent ultrastructural studies also indicate that tumour cell types and histological organization similar to those described for adenoid cystic carcinoma occur during histodifferentiation of salivary gland pleomorphic adenoma (Dardick et al. 1983a, b). The characteristic histological pattern of adenoid cystic carcinoma is dependent on the formation of pseudolumina containing proteoglycans and reduplicated basal lamina. Similar, but smaller, lumina of like organization and contents are evident in some cases of pleomorphic adenoma. Both the ultrastructural similarities of the tumour cell types and their organization, in adenoid cystic carcinoma and pleomorphic adenoma, suggest that these tumours have a similar histogenetic basis. The fact that one lesion is malignant and the other benign does not preclude common types of tumour cells and developmental processes.     

An intracapsular carcinoma ex pleomorphic adenoma with lung metastases composed exclusively of benign elements: Histological evidence of a continuum between metastasizing pleomorphic adenoma and carcinoma ex pleomorphic adenoma

Malignant mixed tumors of the salivary glands, encompassing carcinoma ex pleomorphic adenoma (ca ex PA), carcinosarcoma and metastasizing pleomorphic adenoma (mPA), are rare neoplasms. Ca ex PA arises in a pre-existing pleomorphic adenoma (PA). When the malignant component does not breach the capsule of the parent PA, the lesion is termed intracapsular ca ex PA, a neoplasm which is thought to have no metastatic potential. Metastatic deposits of ca ex PA are composed exclusively of malignant elements or mixed benign and malignant components. We describe the case of a 62-year-old female with an intracapsular ca ex PA of the buccal mucosa with subsequent metastases to the lung. The metastatic deposits resembled benign PA with no histological evidence of malignancy. This pattern of spread is described with mPA, an entity that caused controversy in the past regarding its exact classification as a benign or malignant tumor. The possibility that ca ex PA originates from a mPA, with intracapsular ca ex PA representing an intermediate lesion in a histological continuum, is discussed.     

Adenoid cystic carcinoma of the right main bronchus showing squamous differentiation and mimicking mucoepidermoid carcinoma: a case report

Complete dissection of tracheobronchial adenoid cystic carcinoma (TACC) by surgery alone is sometimes difficult and has a greater propensity than tracheobronchial mucoepidermoid carcinoma (TMEC) for its surgical margin to become positive. In addition, TACC is more likely to present distant metastases than TMEC. Considering these facts, TACC and TMEC should be differentiated based on histopathological examination of biopsy specimens. Herein, we present a case of 54-year-old woman with a tumor in the right main bronchus, whose biopsy specimen was difficult to diagnose as TACC or TMEC. The specimen from the rounded protrusion of the tumor showed squamous differentiation, along with the presence of glandular and basaloid cells, making morphological examination alone ineffective in rendering a definite diagnosis. Thus, the addition of immunohistochemical analysis, αSMA and CD43 expression in basaloid cells and c-kit expression in glandular cells, was useful for accurately diagnosing TACC in this case. The squamous component was considered to be neoplastic because of its increased expression of cyclin D1 and overexpression of p16. The surgically resected specimen contained typical morphology of ACC, and the diagnosis of TACC was definitely confirmed.     

Fine-needle aspiration cytology of pleomorphic hyalinized angiectatic tumor: A case report

Pleomorphic hyalinized angiectatic tumor (PHAT) of soft parts is a neoplasm characterized by spindle and pleomorphic cells associated with an angiectatic vasculature. We describe the cytological findings of a fine-needle aspiration biopsy (FNAB) from the right medial knee of a 45-yr-old woman. The aspirate material was entirely submitted in Cytolit solution. The specimen was moderately cellular and was comprised of spindle cells in a background of fibrinous material. The cells varied from small, bland spindle cells with a fine chromatin pattern and inconspicuous nucleoli to larger pleomorphic cells with coarser chromatin and occasional intranuclear inclusions. Most of the cells were arranged singly with sporadic small cluster formation with indistinct cell borders. Rare mononuclear inflammatory cells morphologically compatible with mast cells were identified. The differential diagnosis include solitary fibrous tumor (SFT) and ancient schwannoma, which also shows fibrous-like material and spindle cells that may have intranuclear inclusions.     

气管多形性腺瘤1例并文献复习

目的:探讨气管多形性腺瘤的临床病理特征、诊断和鉴别诊断.方法:分析l例气管多形性腺瘤的临床病理资料、病理结果,并复习文献.结果:肿物大小2.5cm×1.5cm×1.0 cm,表面光滑,不规则结节状,切面灰白,半透明,质软韧,无明显出血和坏死.光镜下由上皮组织和间质组织两种成分构成,上皮细胞呈巢状、条索状及梁状漂浮在软骨黏液样间质背景中,局灶可见到腺样结构,细胞胞浆嗜酸性,无明显细胞异型性和核分裂象.免疫组织化学检查肌上皮细胞CK,S-100和P63阳性表达.腺上皮CK,CK7和CK19标记阳性.结论:气管多形性腺瘤少见,诊断气管内肿瘤时要考虑到这个鉴别诊断,以免漏诊或误诊.未来需要研究更多气管多形性腺瘤病例以进一步完善其临床进程、生物学行为和预后.     

Melanoma in a carcinoma ex pleomorphic adenoma of the parotid gland: a case report and putative histogenesis

A rare example of melanoma arising in carcinoma ex pleomorphic adenoma is presented. The diagnosis, differential diagnosis, and putative histogenesis of the melanoma component are discussed.     

Fine-needle aspiration of a pleomorphic lipoma of the head and neck: a case report

Pleomorphic lipoma is a rare soft-tissue tumor, most commonly seen in the head and neck regions of middle-aged men. Fine-needle aspiration (FNA) of these lesions can present a diagnostic challenge. Its large, hyperchromatic cells and multinucleated forms (floret cells) can easily be mistaken for a malignancy. A patient with a round, well-circumscribed, painless, soft, subcutaneous posterior neck mass for 6 yr presented to our FNA clinic. Aspiration of the mass showed a hypocellular specimen with atypical large and floret cells with fragments of mature fibroadipose tissue in the background. Based on the clinical and cytomorphological findings, a diagnosis of pleomorphic lipoma was suggested, and it was confirmed on excision. This case highlights the need to be aware of unusual benign lesions that may arise in the head and neck region. Knowledge of these benign lesions will help in making the correct cytological diagnosis when these lesions are sampled by FNA.     

A case of matrix-producing metaplastic carcinoma of the breast exhibiting similarities to pleomorphic adenoma on fine-needle aspiration cytology

The distinction between matrix-producing metaplastic carcinoma (MPMC) and pleomorphic adenoma (PA) is sometimes unclear in breast pathology, especially on core needle biopsy. Herein, we presented a 66-year-old woman with MPMC of the breast that looked like PA on fine-needle aspiration cytology (FNAC). On FNAC, the appearance of abundant myxoid matrix along with cellular clusters composed of monotonous cellular populations looked like salivary PA, which we were familiar with owing to the frequency in routine pathological practice. Thus, the possibility of breast PA, the counterpart of salivary PA, was considered. However, the tumor location was different from where breast PA frequently occurs, i.e. the retroareolar region. Therefore, we eliminated the possibility of breast PA and avoided the erroneous cytological diagnosis. It is should be kept in mind that MPMC can look like PA on FNAC.     

Cyclin D1 and p16 expression in pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the parotid gland

AIMS: To compare cyclin D1 and p16(ink4) (p16) expression in normal tissue, pleomorphic adenoma (PA) and carcinoma ex pleomorphic adenoma (CXPA) of the parotid gland. METHODS AND RESULTS: Immunohistochemistry was used to examine cyclin D1 and p16 expression in 43 parotid tumours (29 PAs and 14 CXPAs). Cyclin D1 and p16 were both significantly more likely to be expressed in the neoplastic than in the normal epithelial and stromal components of PA and CXPA (P < 0.001 and P < 0.005, respectively). Cyclin D1 was more likely to be expressed in the malignant components of CXPA than in the benign components of PA (50% versus 31% and 31%, respectively), but the trend was not statistically significant. There was no evidence of this association for p16 (corresponding positivity rates 69% versus 81% and 52%). CONCLUSIONS: Our findings provide preliminary evidence of roles for cyclin D1 and p16 in the development of PA and for cyclin D1 in the progression of PA to CXPA.     

Pleomorphic adenoma and carcinoma ex pleomorphic adenoma: immunohistochemical demonstration of the association between tenascin expression and malignancy

AIMS: To investigate tenascin expression in salivary gland tumours. Tenascin is a matricellular protein that has been studied in several tumour types. Its expression has been correlated with tumour morphogenesis as well as with local invasiveness and tumour metastatic behaviour. METHODS AND RESULTS: The distribution pattern of tenascin in a series of 63 pleomorphic adenomas (PA) and 20 carcinomas ex- pleomorphic adenoma (Ca ex PA) was studied immunohistochemically. Ten normal adult salivary glands were used as controls. Tenascin surrounded the excretory ducts of normal adult salivary gland tissue. It was absent in the basement membrane compartment of both benign and malignant mixed tumours. In the interstitial compartment of the extracellular matrix, the fibro-hyaline type expressed tenascin in a statistically significantly (P < 0.001) lower number of PA cases (25%) in comparison with both malignant and benign areas of Ca ex PA (75% and 90%, respectively). In the Ca ex PA group, a statistically significantly difference (P < 0.001) was found in the frequency of tenascin deposits around aggregates of neoplastic cells between metastasizing (73%) and non-metastasizing neoplasms (0%). CONCLUSIONS: These findings strongly support the hypothesis that tenascin deposition is involved in the mechanisms of malignant transformation of pleomorphic adenomas into carcinomas as well as being associated with clinical disease progression.     

Spindle cell lipoma mimicking pleomorphic adenoma: A diagnostic challenge on cytology

Spindle cell lipoma (SCL) is a benign neoplasm of mature adipose tissue mostly located in the neck, back, and shoulder region. It is composed of a variable admixture of adipocytes, benign spindle cells, and collagen fibres. While the histopathologic features of SCL are quite characteristic and well described, a cytologic diagnosis of SCL might be challenging. We present a case of a 36‐year‐old female with a swelling in the left preauricular region since last 6 mo. On fine needle aspiration, a diagnosis of lipomatous pleomorphic adenoma (PA) was rendered because of the presence of benign spindle‐shaped cells, adipocytes, and abundant myxoid material. However, on histopathologic examination, the diagnosis was SCL which was confirmed by immunohistochemistry. Preauricular region is a rare site of occurrence of SCL. An acquaintance with its varied cytomorphologic features and a knowledge of its unusual sites of occurrence is essential to prevent its misdiagnosis as other myxoid benign and malignant spindle cell lesions.     

Fine-needle aspiration of an adenoid cystic carcinoma of the larynx mimicking a thyroid mass

Adenoid cystic carcinoma (ACC) is most often primary in the major and minor salivary glands but can also arise from the submucosal seromucinous glands of the larynx and trachea. We report a case of adenoid cystic carcinoma of the larynx that presented as a diffuse swelling in the thyroid area. Fine-needle aspiration (FNA) was consistent with a neoplastic process, which was difficult to classify further but was felt to be of thyroid origin. Subsequent gross and histopathologic examination showed the lesion to represent an ACC arising from the larynx. This case highlights the need to be aware of unusual lesions that may arise in the region of the thyroid. Knowledge of these non-thyroidal lesions that can clinically mimic a thyroid mass will help in making the correct cytologic diagnosis when these lesions are sampled by FNA.     

Salivary duct carcinoma ex pleomorphic adenoma: Analysis of the findings in fine-needle aspiration cytology and histology

Salivary duct carcinoma (SDC) is an uncommon and highly aggressive neoplasm that reveals histopathologic features resembling infiltrating duct carcinoma of the breast and prostate. SDC arising on the basis of preexisting pleomorphic adenoma (PA) is very rare. This report describes the fine-needle aspiration (FNA) cytology of a case of SDC ex PA. FNA smears were cellular with cells with large, pleomorphic nuclei, some prominent nucleoli, and finely vacuolated cytoplasm. The neoplastic cells were forming groups, sheets, and papillary structures and a cribriform pattern was present in some sheets. Mitotic figures were frequently seen. Necrosis was prominent in the background. Histologic sections of the tumor revealed areas of comedo carcinoma, papillary carcinoma, and infiltrative carcinoma as well as multiple foci of PA. The presence of a cribriform pattern, tumor cells resembling breast ductal carcinoma cells, and a necrotic background are helpful features for an accurate cytodiagnosis of SDC. Diagn. Cytopathol. 1998;19:201–204. © 1998 Wiley-Liss, Inc.     

涎腺恶性多形性腺瘤161例临床病理分析

目的分析涎腺恶性多形性腺瘤（malignant pleomorphic adenoma,MPA）的临床病理特征。方法对经病理复片诊断为MPA的161例临床病理材料进行回顾性分析。结果161例MPA中,152例为原发性肿瘤、7例为局部复发性肿瘤、2例为肿瘤颈淋巴结转移灶。152例原发MPA中发生于腮腺85例、腭部39例、颌下腺21例、颊部3例、唇部2例、磨牙后区1例、上颌骨1例;男性95例,女性57例,男女比为1．7：1;发病年龄为27～92岁,平均59岁。恶性成分的组织学类型包括肌上皮癌62例、非特异性腺癌59例、腺样囊性癌8例、黏液表皮样癌7例、导管癌3例、腺鳞癌3例、上皮-肌上皮癌3例、癌肉瘤3例、未分化癌2例、腺泡细胞癌1例、黏液腺癌1例。组织学高、中、低度恶性的分别为45、69、38例。同一肿瘤中恶性成分≤50％的为21例,〉50％的为131例。侵袭性、微侵袭性、非侵袭性癌分别为106、10、33例。侵袭性癌、组织学分级与肿瘤发生颈淋巴结转移之间有显著相关性（P值均〈0．01）。结论MPA多见于中老年男性,好发于腮腺;临床表现多为无痛渐大性肿块,以近期生长迅速为特征;组织学表现为常同时具有良性多形性腺瘤成分和恶性肿瘤成分,侵袭性癌多见,恶性成分常多于良性成分,恶性成分以肌上皮癌和非特异性腺癌为多见;侵袭性癌、组织学分级高度恶性者易发生颈淋巴结转移。