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PubMed2004

Malignant rhabdoid tumor arising from a pleomorphic adenoma.

Malignant transformation of pleomorphic adenomas often occurs in long-standing tumors or tumors with multiple local recurrences. The malignant component is usually a carcinoma. The case reported herein concerns a 60-year-old man who had a malignant rhabdoid tumor arising in a painless parotid mass that remained untreated for 25 years. Malignant rhabdoid tumors are clinically aggressive neoplasms with phenotypic features that resemble rhabdomyomatous differentiation but lack genuine skeletal muscle differentiation. The salient features of rhabdoid tumor cell include large, pleomorphic, and eccentric nucleus and a solitary and prominent intracytoplasmic inclusion that is strongly immunoreactive for vimentin. It is our understanding that this is the first reported case of malignant rhabdoid tumor arising in the parotid gland in the English literature. The pathologic features of our case will be discussed in context with malignant rhabdoid tumors from other parts of the body.

Adenoma, Pleomorphic↗
PubMed2006

Pleomorphic adenoma of the trachea in an 8-year-old boy: a case report.

We report a case of pleomorphic adenoma of the trachea in an 8-year-old boy who required emergency surgery for severe respiratory distress. Chest computed tomographic scan and bronchoscopy showed a relatively large mass in distal trachea and right main bronchus and destruction of the lung parenchyma. The patient was subjected to right carinal resection, pneumonectomy, and pericardial patch tracheoplasty for reconstruction of the trachea. Histopathological examination and immunohistochemical staining of tumor specimens were compatible with pleomorphic adenoma. Postoperative follow-up of this patient for a period of 6 months showed satisfactory results with no complications or tumor recurrence. We present not only a very rare benign tracheal tumor in children but also demonstrate successful usage of a free pericardial patch for tracheal reconstruction, although direct anastomosis failed to provide an adequate anastomotic lumen.

Adenoma, Pleomorphic↗
PubMed2005

Myoepithelial carcinoma ex pleomorphic adenoma of salivary glands: a problematic diagnosis.

We report the case of a 77-year-old woman who presented with a 6-year history of pleomorphic adenoma with multiple recurrences. Despite the clinical suspicion of a malignant process, the detection of myoepithelial carcinoma ex pleomorphic adenoma was not achieved by means of a preoperative biopsy or a frozen section removed intraoperatively, as the lesion only showed mild cytological atypia with no frank malignant features. Only a thorough evaluation of the resected tumor enabled the diagnosis of a malignancy. We discuss the difficulties that may be encountered in attempting to diagnose these rare myoepithelial lesions by means of small biopsy specimens.

Adenoma, Pleomorphic↗
PubMed2002

Translocation, deletion/amplification, and expression of HMGIC and MDM2 in a carcinoma ex pleomorphic adenoma.

Carcinoma ex pleomorphic adenoma (CexPA) is a carcinoma developing within a pre-existing benign pleomorphic adenoma (PA). Here we describe the identification and characterization of a series of genetic events leading to translocation, deletion/amplification, and overexpression of the HMGIC and MDM2 genes in a CexPA at an early stage of development. The tumor had a pseudodiploid stemline karyotype with a del(5)(q22-23q32-33) and a t(10;12)(p15;q14-15). In addition, there were several sidelines with double minute chromosomes (dmin) or homogeneously staining regions (hsr). Fluorescence in situ hybridization (FISH) mapping revealed that the 12q14-15 breakpoint was located centromeric to HMGIC and that the entire gene was juxtaposed to the der(10) chromosome. Detailed analysis of cells with dmin and hsr revealed that HMGIC and MDM2 were deleted from the der(10) and that the dmin and hsr were strongly positive for both genes. Southern blot analysis confirmed that both HMGIC and MDM2 were amplified and that no gross rearrangements of the genes had occurred. Immunostaining revealed that the HMGIC protein was highly overexpressed particularly in the large polymorphic cells within the carcinomatous part of the tumor. These findings suggest that amplification and overexpression of HMGIC and possibly MDM2 might be important genetic events that may contribute to malignant transformation of benign PA.

Adenocarcinoma↗
PubMed1983

Pleomorphic adenoma, I: Ultrastructural organization of "epithelial" regions.

Twenty-four major and minor salivary gland pleomorphic adenomas were studied ultrastructurally to determine the growth patterns, organization, and cytologic modifications of the proliferating neoplastic cells. In compact and highly cellular regions, two cell types--luminal epithelial and myoepithelial--could often be identified; their organization mimicked that of the normal salivary gland duct or acinar unit. Results of the study indicate that the principal proliferating tumor cell is a structurally modified myoepithelial cell that frequently shows squamous differentiation. At the immediate margins of cellular regions of many tumor cells, gradual dedifferentiation of modified myoepithelial cells with a loss of squamous features occurs, although in some cells the squamous features are retained to varying degrees. Within cellular regions, the earliest development of matrix occurs in relation to small, basal lamina-lined extracellular spaces between myoepithelial-like cells. Modifications of such intercellular spaces are helpful in tracing the development of myxoid zones and the evolution of cell types in this unique region. The authors postulate that salivary gland pleomorphic adenomas result from the neoplastic transformation of the complete ductal-acinar unit rather than from one particular ductal "reserve" cell.

Adenoma, Pleomorphic↗
PubMed1983

Pleomorphic adenoma, II: Ultrastructural organization of "stromal" regions.

Findings from an ultrastructural study of 24 major and minor salivary gland pleomorphic adenomas suggest that the principal cell type in the myxoid and chondromyxoid regions of these tumors is a structurally modified myoepithelial cell. This interpretation is based on findings in the transitional zone between myxoid regions and compact cellular areas that have a ductal-acinar organization, that is, are composed of luminal epithelial and modified myoepithelial cells. Survey-type low-power electron micrographs allowed appreciation of the original orientation of the major proliferating component of these tumors to the perimeter of ductal-acinar units. The low-power electron micrographs also revealed residual features of this organization, the early development and subsequent sequential alteration of matrix compartments as tumor cells became increasingly separated by extracellular products, and a variety of myoepithelial cell modifications, such as squamous and chondroid metaplasia, resulting from neoplastic induction. According to the authors' interpretation, modified myoepithelial cells in myxoid and chondromyxoid regions form a continuum with similar tumor cells in transitional and solid areas, forming what can be visualized as markedly expanded and merging ductal-acinar units that tend to converge with similarly altered adjacent neoplastic ductal-acinar units. Thus, a multiplicity of processes are involved in the formation of the complex and varied histologic patterns that characterize pleomorphic adenomas.

Adenoma, Pleomorphic↗
PubMed1996

Mutations associated with carcinomas arising from pleomorphic adenomas of the salivary glands.

Pleomorphic adenoma (PA) is the most common benign tumor of salivary glands. Carcinomas in pleomorphic adenomas (CPAs) may arise by malignant transformation of the epithelial components of PAs. Occasionally, transitional zones containing cells with histological features intermediate between those of the benign PA and carcinomatous components of CPA are identified. After careful microdissection of archival microslides, the authors studied 12 cases of CPAs and their attendant adenomatous and transitional areas for mutations in the p53, RB, and K-ras genes, and at chromosomal loci 5q and 9p. The authors failed to find mutations in the K-ras gene or 9p locus. A relatively high rate of mutations (loss of heterozygosity [LOH] and microsatellite alterations) at the p53 gene were detected in CPAs (58%), and at somewhat lower frequencies at the RB gene (33%) and chromosomal location 5q (17%). Mutational frequency in the associated transitional and adenomatous areas were slightly lower than in the corresponding CPAs. No mutations were detected in adenomatous or transitional areas unless they also were present in the corresponding CPAs. Mutations of these three genes were absent in four cases of CPA, and in seven PAs without malignant change. These findings indicate that most CPAs arise from adenomas as the result of mutations in the three genes, especially p53. In addition, other, as yet unidentified genes may also be involved both in the development of PA and in its malignant progression to CPA. Mutational analysis of PAs may provide information of prognostic importance.

Adenocarcinoma↗
PubMed1997

Nasal pleomorphic adenoma with skeletal muscle differentiation: potential misdiagnosis as rhabdomyosarcoma.

Pleomorphic adenoma can show diverse lines of differentiation in the epithelial and myoepithelial elements, such as cartilage, bone, and fat. Myoid differentiation, however, has not been documented. We report an unusual case of nasal pleomorphic adenoma which shows focal skeletal muscle differentiation. The tumor was discovered only after successful radiation therapy for an undifferentiated carcinoma of the nasopharynx. Apart from being of morphological interest, the presence of cells with skeletal muscle differentiation also raises the practical issue of possible confusion with rhabdomyosarcoma in a biopsy. The distinguishing features are lack of cytological atypia and presence of a neoplastic glandular element.

Adenoma, Pleomorphic↗
PubMed1994

Clear cell epithelial-myoepithelial carcinoma arising in pleomorphic adenoma of the lacrimal gland.

BACKGROUND: A 63-year-old man had an 8-year history of painless proptosis, which had noticeably increased over the last 2 months. A mass was palpable in the left lateral canthus. Computed tomographic studies showed a globular mass with small foci of calcification involving the lacrimal gland. After an incisional biopsy, a histologic diagnosis of clear cell epithelial-myoepithelial carcinoma was made and an orbital exenteration was performed. FINDINGS: Results of histologic examination of the mass showed a partially encapsulated, clear cell epithelial-myoepithelial carcinoma with an associated pleomorphic adenoma (benign mixed tumor). Immunohistochemical studies disclosed strong immunoreactivity to cytokeratin (AE1/AE3), epithelial membrane antigen, S-100 protein, and alpha-actin. CONCLUSION: Although a clear cell myoepithelial carcinoma rarely has been reported in association with a pleomorphic adenoma of the submandibular gland, to the authors' knowledge, this combination has never been reported in the lacrimal gland, nor has a clear cell epithelial-myoepithelial carcinoma ever been reported in this anatomic location. The differential diagnosis of lesions with prominent clear cells involving the lacrimal gland is extensive and includes clear cell variants of acinic cell carcinoma and oncocytoma, mucoepidermoid carcinoma, and others.

Adenocarcinoma, Clear Cell↗
PubMed1998

Recurrent pleomorphic adenomas of the parotid gland: clinical evaluation and long-term follow-up.

We report 94 patients with recurrent pleomorphic adenomas of the parotid gland who were referred to our clinics after operations elsewhere. In 78 patients (83%) enucleation was the surgical technique used to remove the tumour. Patients with more than one recurrence were significantly younger than patients who had only one. Many recurrent adenomas (44%) were multifocal. In 20 (21%) further recurrences became obvious after we had operated on them. The mean time interval before recurrence ranged from 7.3 to 10.1 years. Twenty patients (14%) had persistent motor disorders of the facial nerve after operation for recurrence (n = 143). Twenty eight of the 84 patients from whom follow-up data could be obtained developed Frey's syndrome (33%). Our data support the importance of an adequate initial operation to avoid recurrences of pleomorphic adenomas in the parotid gland.

Adenoma, Pleomorphic↗
PubMed1986

Pleomorphic adenoma of the cheek.

The mucosa of the cheek is a relatively rare site of occurrence for intraoral pleomorphic adenoma. A case of a large pleomorphic adenoma of the cheek is reported and a review of this lesion in the cheek is presented.

Adenoma, Pleomorphic↗
PubMed1996

Parathyroid hormone-related peptide: immunolocalisation in normal salivary glands and in pleomorphic adenomas.

Parathyroid hormone-related peptide (PTHrP) has been shown to be produced as an early step in the differentiation sequence and is considered to be a marker of some progenitor cells. We investigated the presence and distribution of PTHrP in 7 normal parotid glands and in 18 salivary pleomorphic adenomas (PA). Localisation of PTHrP was studied by immunohistochemistry with a three-step unlabelled peroxidase-antiperoxidase method. In the normal glands PTHrP is found mainly in the basal and dark cells, and to a lesser extent in the light cells of the ducts. In PA the inner layer of tubulo-ductal structures and all cells of the cyst-like structures show strong positivity for PTHrP. Scattered cells in the dense clusters also stain strongly. Virtually all tumour cells in myxoid and chondroid areas are devoid of staining. In clusters of squamous metaplasia, most cells are slightly positive and scattered cells are stained strongly. PTHrP contributes to cellular differentiation and is also related to keratinisation. We suggest that the PTHrP-positive inner layer cells in pleomorphic adenomas represent a step in the squamous differentiation and in the further elaboration of the tubulo-ductal structures.

Adenoma, Pleomorphic↗
PubMed2002

Pleomorphic adenoma of the parotid gland: is long-term follow-up needed?

INTRODUCTION: Pleomorphic adenoma is a slow-growing benign salivary tumour most commonly arising in the parotid gland. Macroscopically it has a surrounding capsule from which it can be enucleated-often the treatment used in the past. These tumours do not have a true capsule but can press surrounding normal salivary gland, frequently having finger-like extensions into the normal tissues. Recurrence, or more accurately residual disease, is thought to be due to these small islands of tumour which can be left behind at surgery, in particular enucleation which is associated with high recurrence rate. The current, most common practice is the excision of these tumours through superficial parotidectomy and postoperative follow-up. However, is long-term follow-up necessary and does it reduce the morbidity from tumour recurrence? METHODS: We reviewed the charts of 182 patients who underwent parotid surgery operated upon by a single surgeon (RKM) between 1973 and 1999. We included only 58 cases of pleomorphic adenomas removed by superficial parotidectomy. We excluded cases that had follow-up of less than 12 months and cases which had previous surgery elsewhere. Adequate tumour excision and the integrity of the capsule were ascertained intra-operatively, and this was confirmed by postoperative histology. RESULTS: In our study we had 34 females, mean age of 58, and 24 males, mean age of 50. The average follow-up was 6 years with a range of 1-23 years. We had no permanent facial nerve dysfunction, and we recorded only one recurrence (1.7%). CONCLUSION: Provided adequate excision of the tumour with intact capsule and histological confirmation are achieved, long-term follow-up is unnecessary and can be replaced by patient education and self-examination.

Adenoma, Pleomorphic↗
PubMed2003

Pleomorphic adenoma originated from the inferior nasal turbinate.

Although pleomorphic adenoma is the most common benign neoplasm of the salivary glands, it has also been reported to be present in the neck, ear, mediastinum, external nose and nasal cavity. Intranasal localization of this lesion is very rare and mainly originates from the nasal septum. From wherever the lesion originates, the main treatment modality should be surgical. We presented a very rare case of intranasal pleomorphic adenoma originated from the inferior nasal turbinate. Due to the expansile nature of the lesion, a midfacial degloving approach was preferred.

Adenoma, Pleomorphic↗
PubMed1997

A case of pleomorphic adenoma of the epiglottis. Bilateral vocal-cord paralysis after YAG laser surgery.

Pleomorphic adenoma of the larynx is a rare disorder, and until recently has been treated mainly by approaches involving pharyngotomy. We encountered a case of pleomorphic adenoma originating from the laryngeal surface of the epiglottis and removed it using a YAG laser through a suspension laryngoscope. This case was complicated by delayed-onset bilateral vocal-cord paralysis, the causes of which are also discussed.

Adenoma, Pleomorphic↗
PubMed1998

Metastasizing pleomorphic adenoma: a report of three cases.

Three cases of metastasizing pleomorphic adenoma are described. All three had a history of incomplete surgery of the primary tumour and several surgical procedures for local recurrences before systemic metastases became apparent. The histology of the primary tumour, recurrences and metastases were typical of pleomorphic adenoma. In view of the lack of information in the literature, it is concluded that inadequate surgical procedures, such as incomplete surgery or enucleation, leading to multiple recurrences, appear to be a prerequisite for the development of systemic disease.

Adenoma, Pleomorphic↗
PubMed1993

Local capsular dissection of parotid pleomorphic adenomas.

Local capsular dissection as described by HANCOCK11 for the treatment of parotid pleomorphic adenomas is discussed. The results of 71 primary parotid pleomorphic adenomas are described, including a 5.6% recurrence rate. This method has the advantage that less facial nerve weakness and Frey's syndrome are seen than with superficial or complete parotidectomy. The recurrence rate appeared to be somewhat higher than with most other series.

Adenoma, Pleomorphic↗