Female, 10 years old. Large tissue mass fixed to the lower jaw with ulceration of the overlying skin
Diagnosis JUVENILE (AGGRESSIVE) FIBROMATOSIS (DESMOID TUMOR)
Comment: Aggressive fibromatosis consists of elongated fibroblasts separated by collagen and arranged in interlacing fascicles. The cells have bland cytologic features. Mitoses are rare. At the periphery the lesion may invade adjacent fatty or muscle tissue.
In spite of its innocuous histologic appearance, the lesion may show extensive local invasive growth necessitating major surgical procedures. In children aggressive fibromatosis has a predilection for the head and neck region. Histologically, the lesion should be distinguished from fibrosarcoma at the one side and reactive fibrosis or nodular fasciitis at the other side. Although fibromatosis may contain some cells that, due to myofibroblastic differentiation, may show positivity for smooth muscle markers, a more extensive positivity for smooth muscle makes a diagnosis of myofibromatosis more likely, a lesion with a far less aggressive behavior.
References:
1. Fowler CB, Hartman KS, Brannon RB. Fibromatosis of the oral and paraoral region. Oral Surg Oral Med Oral Pathol 1994: 77, 373-386.
2. Batsakis JG, Raslan W. Extra-abdominal desmoid fibromatosis. Ann Otol Rhinol Laryngol 1994: 103, 331-334.
3. Enzinger F, Weiss SW. Soft tissue tumors. 3rd ed. Mosby, St. Louis, 1994: 201-229; 231-268.
4. Lucas DR, Shroyer KR, McCarthy PJ, Markham NE, Fujita M, Enomoto TE. Desmoid tumor is a clonal cellular proliferation: PCR amplification of HUMARA for analysis of patterns of X-chromosome inactivation. Am J Surg Pathol 1997: 21, 306-311.
Female, 68. Discrete mass in the tail of the right parotid gland. History of dry mouth and possible Sicca syndrome
Diagnosis MALT LYMPHOMA OF THE PAROTID GLAND
(primary salivary gland lymphoma, extranodal marginal zone lymphoma of salivary gland).
Salivary gland MALT lymphomas are usually seen in patients over 50 and there is a marked female predominance. Many cases arise on the background of Sjogren's syndrome; patients with long-standing Sjogren's disease show a 40-fold increase in incidence of salivary lymphoma. In autoimmune conditions such as Sjogren's lymphoid tissue concentrates around salivary ducts leading to proliferation of the epithelial and myo-epithelial cells forming epi-myoepithelial islands. These islands are infiltrated by B-lymphocytes resulting in the production of lympho-epithelial lesions (LELs). At other sites LELs are considered to be indicative of lymphoma, but in the salivary gland this may not be the case, and so the term myo-epithelial sialadenitis or MESA is used to describe this feature. It can therefore be difficult to draw a dividing line between an autoimmune disorder with MESA and a true salivary gland lymphoma. The clinical history may be helpful; sudden unilateral swelling of a gland is suggestive of lymphoma whereas a slow bilateral increase in both glands is more likely to represent Sjogren's. One of the earliest histological signs of MALT lymphoma is an expansion of the region of centrocyte-like cells around the epi-myoepithelial islands. This is usually seen as a halo of paler, often slightly monocytoid, lymphoid cells at the periphery of the epithelial structures. The presence of a halo greater than three cells in thickness is indicative of lymphoma, and such cases will show light chain restriction or clonal bands when analysed with PCR. Salivary gland lymphomas may show colonisation of pre-existing follicles giving a nodular appearance to the tumour. As the disease progresses the pattern becomes that of a diffuse sheets of cells within which are scattered the epi-myoepithelial islands. Centrocyte-like, monocytoid and blastic forms may be present and there may be marked plasma cell differentiation. The blast population can also be quite marked, and it may be difficult to determine when the tumour has transformed to a high-grade lymphoma. Lymph node involvement is usually a late feature; both intraparotid and cervical nodes may be affected.
Molecular studies show monoclonal rearrangement of heavy and light chain immunoglobulin genes in salivary MALT lymphoma. Rearrangement may also be detected in histologically benign examples of MESA; it is postulated that the lymphoma develops due to the emergence of a B-cell clone arising in an autoimmune condition. At the genetic level salivary MALT lymphoma does not show the t(14:18) translocation found in follicle centre cell lymphomas; there is evidence emerging that trisomy 3 is common in MALT lymphomas from a variety of sites.
In general salivary MALT lymphoma is a low-grade indolent tumour that can remain localised for many years. The lesion may disseminate to local lymph nodes or may be associated with the development of lymphoma at other MALT sites such as lung and stomach. Bone marrow involvement is rare. Local treatment by surgery and/or radiotherapy is usually sufficient to control the disease.
References:
1. Balm AJ, Delaere P, Hilgers FJ, Somers R, Van Heerde P. Primary lymphoma of mucosa associated lymphoid tissue (MALT) in the parotid gland. Clinical Otolaryngology 1993;18:528-32
2. DiGiuseppe JA, Corio RL, Westra WH. Lymphoid infiltrates of the salivary glands: pathology, biology and clinical significance. Current Opinion in Oncology 1996;8:232-7
3. Diss TC, Wotherspoon AC, Speight P, Pan L, Isaacson PG. B-cell monoclonality, Epstein Barr virus, and t(14;18) in myoepithelial sialadenitis and low-grade B-cell MALT lymphoma of the parotid gland. Am J Surg Pathol 1995;19:531-6
4. Jordan RC, Speight PM. Lymphoma in Sjogren's syndrome. From histopathology to molecular pathology. Oral Surg, Oral Med, Oral Pathol 1996;81:308-20
5. Kruize AA, Hene RJ, van der Heide A, Bodeutsch C, de Wilde PC, van Bijsterveld OP, de Jong J, Feltkamp TE, Kater L, Bijlsma JW. Long-term followup of patients with Sjogren's syndrome. Arthritis & Rheumatism 1996;39:297-303
6. Wolvlus EB, van der Valk P, van der Wal JE, van Diest PJ, Huijgens PC, van der Waal I, Snow GB. Primary non-Hodgkin's lymphoma of the salivary glands. An analysis of 22 cases. J Oral Pathol Med 1996;25:177-181
Female, 70. Presented with "glue" ear and a three month history of dysphagia and dysphonia. Examination revealed a huge tonsillar mass and bilateral cervical lymph nodes. A tracheotomy and nodal biopsy was performed. Diagnosis MANTLE CELL LYMPHOMA
(centrocytic lymphoma, diffuse small cleaved lymphoma)
Mantle cell lymphoma is a well-recognised entity and commonly involves the upper respiratory tract. This condition makes up approximately 3 to 4% of all non-Hodgkin's lymphomas, has a median age of presentation of 60 and a male-to-female ratio of 4:1. It most frequently presents as widespread disease; 90% of patients present with generalised lymphadenopathy and 90% have Stage IV disease at presentation. When first diagnosed, 60% of patients are found to have splenomegaly and 80% have an involved bone marrow. The disease seems to also have a predilection for certain extranodal sites, in particular Waldeyer's ring and the gastro-intestinal tract. Between 20 and 30% of patients show involvement of either or both these regions at presentation. (Multiple lymphomatous polyposis of the bowel is one manifestation of mantle cell lymphoma.) Histologically the pattern may be diffuse or nodular. The nodularity is due to colonisation of pre-existing follicles by the neoplastic cells. The cells themselves are usually small or medium-sized but larger forms may be seen in in "transforming" or "anaplastic" mantle cell lymphoma. The nuclei are typically irregular in outline ("cleaved") and lack prominent nucleoli. Cleaved cells may be seen in the peripheral blood. Immunohistochemistry shows a monoclonal B-cell population, often with an IgM phenotype. The high mitotic rate, as shown by proliferation markers, may be useful in distinguishing mantle cell lymphoma from lymphocytic lymphoma (which has a low number of cells in cycle) and from lymphoblastic lymphoma, in which there is a very high percentage of cells in cycle. The cells have a characteristic cytogenetic abnormality t(11;14)(q13;q32). This leads to an error in V-D-J joining so that the putative oncogene bcl-1 is moved into proximity with the immunoglobulin heavy-chain enhancer region. This in turn results in over-expression of cyclin D1, which can be detected immunohistochemically. In terms of prognosis mantle cell lymphoma behaves in an aggressive fashion. The median survival is between 3 and 4 years and very few patients are cured with conventional chemotherapy.
References:
1. Alkan S, Schnitzer B, Thompson JL, Moscinski LC, Ross CW. Cyclin D1 protein expression in mantle cell lymphoma. Annals of Oncology 1995;6:567-570
2. de Boer CJ, van Krieken JH, KluinNelemans HC, Kluin PM, Schuuring E. Cyclin D1 messenger RNA overexpression as a marker for mantle cell lymphoma. Oncogene 1995;10:1833-1840
3. Weisenberger DD, Armitage JO. Mantle cell lymphoma - an entity comes of age. Blood 1996;87:4483-4494
Female age 41, Unilateral nasal obstruction.Diagnosis OLFACTORY NEUROBLASTOMA
Olfactory neuroblastoma arises from reserve cell of the olfactory neuroepithelium high in the roof of the nose. It is an uncommon neoplasm which shows two peaks of incidence, in the second and sixth decades. There is no predilection for either sex. Presentation is usually with unilateral nasal obstruction or epistaxis. Grossly, the neoplasm appears as a polypoid mass protruding from the roof of the nasal cavity.
Typically, olfactory neuroblastoma appears in one of two patterns, or a mixture of both. Most easily recognisable are lobular groups of small cells with eosinophilic fibrillary intercellular matrix material. The tumour cells have a round nucleus, fine chromatin and little cytoplasm. Nuclear pleomorphism is not conspicuous but mitotic activity is variable. Both gland-like Flexner-type true rosettes or Homer-Wright pseudorosettes may be seen. The latter are considerably more common than the former. Ganglion cells may be found on rare occasions. The intercellular stroma is typified by aggregates of gaping, thin-walled blood vessels.
The second pattern is of a diffuse proliferation of tumour cells without lobule formation or the characteristic vascular pattern.
Both patterns may be seen together in the same case.
The features described above enable diagnosis in the majority of cases. Perhaps the most useful immunohistochemical finding, seen in about 75% of cases, is of S-100 positive Schwann cells at the periphery of the lobules of tumour cells. Neurone-specific enolase is found in the tumour cells in a high proportion of cases as is synaptophysin. Cytokeratin positivity is more variable ,and is found in only about a third of cases.
Olfactory neuroblastoma is best treated by a combination of surgery and adjuvant radiotherapy or chemotherapy. Relapse may be in the form of local recurrence or either nodal or distant sprad. Five year disease-free survival does not indicate cure since recurrence may occur after many years.
References:
1. Taxy JB, Bharani NK,Mill SE, Frierson HF Jr, Gould VE. The spectrum of of olfactory neural tumors. A light-microscopic immunohistochemical and ultrastructural analysis. Am J Surg Pathol 1986;10:687-695
2. Olfactory neuroblastoma. An immunohistochemical, ultrastructural, and flow cytometric study. Hirose T, Scheithauer BW, Lopes MB, Gerber HA, Altermatt HJ, Hurner SG, VandenBerg SR. Cancer 1995; 76(1):4-19.
3. Treatment of olfactory neuroblastoma. A report of 11 cases. Jekunen AP, Kairema KJ, Lehtanen HP, Kajanti MJ. Am J Clin Oncol 1996 ; 19(4):375-378
Male age 59, heavy smoker and moderate drinker of alcohol presented with progressive hoarseness. A diagnosis of laryngeal carcinoma was made and total laryngectomy was performed. The patient died twelve months later with regional and distant metastases.
DIAGNOSIS ADENOSQUAMOUS CARCINOMA OF LARYNX
Histology: The tumor is characterised by a complex pattern in which infiltrating cords and nests of moderately differentiated keratinizing squamous epithelium are predominant. These squamous epithelial cells become poorly differentiated at the invasive parts, showing marked pleomorphic nuclei and frequent mitotic figures. The neoplastic growth originates from the covering squamous epithelium, where areas of squamous cell carcinoma in situ and also of microinvasion are seen. In addition, mainly at the deeper parts, there is evidence of ductular formation and presence of mucin producing cells, which stain positively for alcian blue and mucicarmine. The mucin producing cells and ducts are clearly neoplastic, showing markedly atypical nuclei. They are different from the normal seromucous glands of the laryngeal mucosa, which are also seen.
Discussion: Adenosquamous carcinoma is an uncommon neoplasm of the upper aerodigestive tract most frequently identified in larynx, hypopharynx, oral cavity and sinonasal tract (1), as well as in esophagus (2).
Histologically, it is characterized by the simultaneous presence of squamous cell carcinoma and adenocarcinoma (3). Both patterns may be admixed or separated. Squamous cell carcinoma is mostly seen in the surface with areas of carcinoma in situ component. Adenocarcinoma is commonly found at the deeper invasive parts. The intraluminal and intracellular material of the glandular component is mucicarmine positive. Mucous cell differentiation may be seen, but is not a prerequisite for diagnosis in the presence of well developed glands.
The main differential diagnosis of adenosquamous carcinoma is mucoepidermoid carcinoma (4). In the past some authors did not distinguish between adenosquamous and high grade mucoepidermoid carcinoma (5). There are five differential criteria: a) Presence of squamous cell carcinoma in situ mostly in the surface epithelium and occasionally in the ducts of the seromucous glands, a feature typical of adenosquamous carcinoma and absent in mucoepidermoid carcinoma. b) Prominent separated foci of squamous cell carcinoma and adenocarcinoma. In mucoepidermoid carcinoma both patterns are closely intermingled. c) Foci of squamous epithelium with marked keratinization in adenosquamous carcinoma. Keratinization is not seen in the epidermoid component of mucoepidermoid carcinoma. d) Intermediate cells, which are typical of mucoepidermoid carcinoma, are absent in adenosquamous carcinoma by light microscopy. e) Severe nuclear pleomorphism and atypicality in adenosquamous carcinoma. High-grade mucoepidermoid carcinoma is less atypical and less aggressive than adenosquamous carcinoma (4,6). It also shows better survival than adenosquamous carcinoma
The histogenesis of both entities is also different. The 1991 WHO classification of salivary gland tumors did not include adenosquamous carcinoma among the tumors of salivary glands (7). Adenosquamous carcinoma is considered to originate from the reserve or basal cells of the covering squamous epithelium which undergoes divergent differentiation (3). Mucoepidermoid carcinoma is considered to originate from the cells of the salivary gland excretory and intercalated ducts (8). However the suggestion was made that there is a continuum of these two carcinomas (5). An experimental model of adenosquamous carcinoma has been recently developed, proving that this tumor does not originate from salivary or seromucous glands, and providing support for its origin from the reserve cells of the squamous epitheium (9).
References:
1. Gerughty R.M., Hennigar G.R., Brown F.M. Adenosquamous carcinoma of the nasal, oral and laryngeal cavities. Cancer 22:1140-1154, 1968.
2. Bombí J.A., Riverola A., Bordas J.M. and Cardesa A. Adenosquamous carcinoma of the esophagus. A case report. Path. Res. Pract. 187:514-519, 1991.
3. Hyams V.J., Batsakis J.G., Michaels L. Tumors of the upper respiratory tract and ear. Atlas of Tumor Pathology. Second Series. Fascicle 25. AFIP. Washington, 104-107, 1988.
4. Luna MA. Salivary gland neoplasms. In: Surgical Pathology of laryngeal neoplasms. Ed. Ferlito A. Chapman and Hall Publ. 1996, pag. 257-294.
5. Damiani JM, Damiani KK, Hanck K et al. Mucoepidermoid-adenosquamous carcinoma of the larynx: a report of 21 cases and review of the literature. Otolaryngol. Head Neck Surg 89:235-243, 1981.
6. Evans H.L. We have met the enemy, but it's another neoplasm (letter). Am J Clin Pathol 82:512-513, 1984.
7. Seifert G, Sobin LH. WHO histological typing of salivary gland tumours. 2nd ed. Berlin, Springer-Verlag, 1991.
8. Dardick I., Van Nostrand AWP. Morphogenesis of salivary gland tumors. A prerequisite to improving classifications. In:Pathol. Annual Part 1, Rosen P.P. and Fechner R.E. (Eds) 1-53, 1987.
9. Cardesa A., Bombí J.A., Pera M., Fernandez P.L., Campo E., Pera C., Mohr U. Spectrum of glandular differentiation in experimental carcinoma of the esophagus induced by 2,6-dimethylnitrosomorpholine under the influence of esophagojejunostomy. Exp Toxic Pathol; 46:41-49, 1994
Female, 84 years. Hard "cyst" on the lower lip. Biopsy followed by wedge resection.
Diagnosis MINOR SALIVARY GLAND: HYALINIZING CLEAR CELL CARCINOMA.
Pathological Findings.
The tumour is deep to the epithelium, and is composed of lobules of clear cells set in a hyalinized collagenous stroma. There is little pleomorphism and mitotic figures are rare. The tumour invades soft tissue and possibly nerves, and extends to one margin. The cells contain plentiful glycogen, but no mucin. High MW (Dako-) keratin +++, CAM 5.2, S-100 protein, smooth muscle actin - all negative. EM - some surface microvilli, but no cytoplasmic filaments.
Discussion.
The unqualified terms "clear cell tumour" or "clear cell carcinoma" are not diagnostic entities, because many different salivary neoplasms (and tumour-like lesions) may be composed partly or completely of cells with clear cytoplasm. These can be divided into tumours in which clear cell change is the usual microscopic appearance, and those which are not usually composed of clear cells but which have relatively uncommon clear cell variants. Examples of the latter include acinic cell carcinoma, the clear cell variant of which accounts for 6% of cases. Similarly, mucoepidermoid and adenoid cystic carcinomas as well as benign myoepithelioma have infrequent yet well recognized clear cell forms.
In addition to the exceptionally rare sebaceous neoplasms, carcinomas in which clear cell change is the usual appearance can be divided into di- and mono-morphic types. The former is epithelial-myoepithelial carcinoma - characterized by small ducts lined by epithelial cells which are surrounded by a layer of myoepithelial cells; the two different populations can be highlighted by immunohistochemistry. Monomorphic clear cell carcinoma was not included in the revised WHO classification, and previous reports have shown inconsistent results with immunohistochemistry, in particular S-100 protein. I feel this is because it comprises two separate entities, one epithelial and the other myoepithelial. The former, hyalinizing clear cell carcinoma, is illustrated in this case, and the other is clear cell malignant myoepithelioma (clear cell myoepithelial carcinoma), and it expresses myoepithelial markers such as S-100 protein, and to a lesser extent, smooth muscle actin.
A further important practical differential diagnosis of any salivary clear cell lesion is metastatic disease, particularly from carcinoma of the kidney, and less frequently thyroid, carcinoma and malignant melanoma. Immunohistochemistry for thyroglobulin, S-100 protein and HMB-45 should identify the latter two tumours, but renal cell carcinoma is best excluded by imaging of the kidney.
References.
1. Milchgrub S, Gnepp DR, Vuitch F, Delgado R, Albores-Saavedra J. Hyalinizing clear cell carcinoma of the salivary gland. Am J Surg Pathol 1994; 18: 74-82.
2. Michal M, Skálová A, Simpson RHW, Rychterová V, Leivo I. Clear cell malignant myoepithelioma of the salivary glands. Histopathology 1996; 28: 309-315.
3. Seifert G. Classification and differential diagnosis of clear and basal cell tumors of the salivary glands. Sem Diag Pathol 1996; 13: 95-103.
Clinical Summary: Female, 13 years old. Intrabony cystic lesion in the
maxillary bone
Diagnosis: ODONTOGENIC KERATOCYST
Comment: Keratocysts are cysts arising in the tooth bearing jaw areas or in the mandibular ramus exhibiting a thin fibrous capsule and a lining of keratinized ssquamous epithelium, predominantly parakeratotic. In the capsule, satellite cysts may be observed. These cysts may recur; therefore recognizing their specific histologic features is of therapeutic relevance.
Keratocysts may occur as part of the basocellular nevus syndrome, an autosomal dominant condition with numerous defects, many involving the axial skeleton.
Not every cyst that shows some keratinisation is a keratocyst. Some cysts may exhibit keratinisation but in the absence of the other specific features as palisading of the basal cells, an epithelial thickness not exceeding 10 cells layers, absence of rete pegs and a corrugated surface, the diagnosis of keratocyst should not be made. These specific features may be lost due to inflammation in which instance the keratocyst is unrecognised and a recurrence may develop.
References:
1. Morgan PR. Cysts and cysts lesion of the jaws. Current Diagn Pathol 1995: 2, 86-93.
2. Vuhahula K. Jaw cysts with orthokeratinization: analysis of 12 cases. J Oral Pathol Med 1993: 22, 35-40
3. Anand VK, Arrowood JP, Krolls SO. Odontogenic keratocysts: a study of 50 patients. Laryngoscope 1995: 105, 14-6.
Female aged 30. 3-4 year history of slowly growing swelling producing buccolingual expansion of the left body of the mandible. Radiographs revealed a well-circumscribed unilocular radiolucency containing areas of diffuse opacity extending from the lower left first premolar almost to the left angle. The inferior dental canal was displaced to the lower border of the mandible.
Diagnosis CEMENTO-OSSIFYING FIBROMA
Ossifying fibroma 9262/0*
Cementifying fibroma 9274/0*
Cemento-ossifying fibroma 9262/0 is recommended
* Morphology code of ICD-O and SNOMED
According to the latest WHO histological classification of odontogenic tumours, cemento-ossifying fibroma (C-OF) is classified as an osteogenic neoplasm and is included in "Neoplasms and other lesions related to bone".
WHO defines C-OF as a "Demarcated or, rarely, encapsulated neoplasms consisting of fibrous tissue containing varying amounts of mineralised material resembling bone and/or cementum".
Formerly, cementifying fibroma was considered to be an odontogenic tumour and was classified separately from ossifying fibroma, whose osteogenic origin was in no doubt; now considered to be one and the same and of osteogenic origin. However, the term C-OF is not universally accepted as it presumes an origin from cementum for the amorphous, cementum-like calcifications seen in some cases and ignores their occurrence in other skul and extra-gnathic fibro-oseous lesions.
C-OF occurs over a wide age range but most present in 3rd and 4th decades; female to male ratio is as high as 5:1; mandible involved far more often than maxilla; mandibular premolar-molar region is commonest site; small lesions often discovered by chance on X-rays; large lesions may cause significant facial asymmetry; pain and paraesthesia very rare. X-rays typically reveal a well-defined, unilocular lesion, sometimes with a sclerotic border; depending on the extent of mineralised tissue formation, it may appear completely radiolucent but usually shows varying degrees of opacity; root divergence or resorption of roots of associated teeth is uncommon. Histopathologically, the lesion is well-demarcated from surrounding bone, a feature which serves to distinguish C-OF from fibrous dysplasia; lesional tissue comprises variably cellular, fibroblastic connective tissue containing varying amounts of mineralised tissue; the latter may be in the form of trabeculae of osteoid and bone or basophilic globular deposits that resemble atypical cementum; both types of mineralisation frequently co-exist.
The circumscribed nature of C-OF, especially smaller lesions, permits enucleation with relative ease; larger leaions often require resection and graftig; prognosis is excellent and recurrence is rarely encountered; no evidence of malignant transformation.
The status of the so-called "juvenile ossifying fibroma" is controversial and the histopathological criteria for its differentiation from classical C-OF are neither well defined nor generally accepted.
References:
1. Eversole LR, Leider AS, Nelson K. Ossifying fibroma: A clinicopathologic study of 64 cases. Oral Surg Oral Med Oral Pathol 60:505-511 1985
2. Johnson LC, et al. Juvenile ossifying fibroma: Its nature, dynamics and origin. Acta Otolaryngol Suppl (Stockh) 488:1-40 1991
3. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumours, 2nd edn. Springer-Verlag, Berlin 1992
4. Makek MS. So-called "fibro-osseous lesions" of tumorous origin: Biology confronts terminology. J Craniomaxillofac Surg 15:154-168 1987
Male age 16 . 8 month history of a painless progressively enlarging swelling of the left mandible with a marked buccolingual expansion. Radiographs showed a well demarcated unilocular radiolucency extending from the second premolar to the third molar region.
Diagnosis ODONTOGENIC FIBROMA
Morphology code of ICD-O and SNOMED
Central odontogenic fibroma: 9321/0*
Peripheral odontogenic fibroma 9322/0*
According to the latest WHO histological classification of odontogenic tumours, the odontogenic fibroma (OF) is categorised as a benign lesion derived from "odontogenic ectomesenchyme with or without included odontogenic epithelium".
WHO defines OF as "A fibroblastic neoplasm containing varying amounts of apparently inactive odontogenic epithelium".
The OF is relatively rare, accounting for <1% of all odontogenic tumours, and controversy exists as to the concept and definition.
The term has been applied to various types of lesion; one resembles the relatively immature and myxoid connective tissue containing islands and strands of odontogenic epithelium, and occasional foci of dystrophic calcification, which often characterises enlarged dental follicles related to unerupted teeth - most oral pathologists would diagnose this as a hyperplastic dental follicle but some have coined the term "simple odontogenic fibroma". Apart from this entity, there exist both intraosseous (central) and gingival (peripheral) lesions designated as OF's.
Central OF has been reported in patients with ages ranging from 9-80 yrs (mean age, 40 yrs); there is a marked female predilection: 7.4 to 1; 60% occur in maxilla with most anterior to the first molar; about 50% of mandibular cases occur posterior to the first molar; smaller lesions asymptomatic; larger lesions may produce localised bony expansion or tooth mobility. On X-ray, smaller lesions tend to be well-defined, unilocular, radiolucencies; larger lesions tend to be multilocular radiolucencies; many lesions exhibit a sclerotic border; root resorption of associated teeth is common. Histopathologically, the so-called "WHO odontogenic fibroma" comprises cellular fibrous connective tissue with collagen fibres arranged in interlacing bundles; odontogenic epithelium in the form of islands and long strands is present throughout the lesion and may be a prominent component; the mesenchymal element may vary from myxoid to densely hyalinised; the lesion is usually encapsulated or sharply demarcated and may contain varying amounts of hard tissue resembling dysplastic cementum or bone; occasionally, the mesenchymal element includes a granular cell population; in the absence of epithelium, the diagnosis of OF should be made with caution. Peripheral OF have similar patterns to those described above but the proliferation of odontogenic epithelium may be such that peripheral ameloblastoma enters the differential diagnosis.
OF responds to local enucleation/curretage; although a few recurrences are reported, the prognosis is very good.
References:
1. Buchner A, Ficarra G, Hansen L. Peripheral odontogenic fibroma. Oral Surg Oral Med Oral Pathol 64: 432-438 1987
2. Gardner DG. The central odontogenic fibroma: An attempt at clarification. Oral Surg Oral Med Oral Pathol 50:425-432 1980
3. Handlers JP, et al. Central odontogenic fibroma: Clinicopathologic features of 19 cases and review of the literature. J Oral Maxillofac Surg 49:46-54 1991
4. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumours. 2nd edn. Springer-Verlag, Berlin 1992
Female, 30 years. Cystic mass below right ear.
Diagnosis PAROTID GLAND: LOW GRADE CYSTIC MUCOEPIDERMOID CARCINOMA WITH A LYMPHOCYTIC RESPONSE.
Pathological Findings.
The parotid tissue contains a partly cystic and partly solid mass of mucinous, intermediate and non-keratinizing epidermoid cells with a heavy, mainly peripheral lymphocytic response. Islands of tumour invade the neighbouring soft tissue, but there is no significant pleomorphism or mitotic activity. The tumour expresses cytokeratins and human milk factor globulin, but neither S-100 protein nor smooth muscle actin.
Discussion:
Seven different types of salivary lesion may present as a lymphoepithelial cyst1:
· Warthin's tumour.
· Benign lymphoepithelial cyst.
· Myoepithelial (Mikulicz) sialadenitis (MESA) with cystically dilated ducts.
· Cystic lymphoid hyperplasia of AIDS.
· MALT lymphoma with cystically dilated ducts.
· Cystic metastases in intraparotid lymph nodes.
· Low grade cystic mucoepidermoid carcinoma with a lymphocytic response.
In MESA, AIDS and MALT lymphoma the lymphocytic infiltrate is intimately involved with the epithelium, and epimyoepithelial islands (lymphoepithelial lesions) are present. Metastases and Warthin's tumour should be obvious, and low grade cystic mucoepidermoid carcinoma can most closely resemble a benign (simple) lymphoepithelial cyst; the carcinoma usually displays invasion, and has larger numbers of mucinous cells.
Mucoepidermoid carcinoma should be graded into one of three microscopic grades, based on the extent of the cystic component, neural invasion, necrosis, cytological pleomorphism and mitotic activity. This assessment has considerable prognostic significance, with death rates due to disease of 3.3% for grade one, 9.7% for grade two and 46.3% for grade three2.
References.
1. Simpson RHW, Sarsfield PTL. Benign and malignant lymphoid lesions of the salivary glands. Current Diagnostic Pathology 1997; 4: in press.
2. Ellis GL, Auclair PL. Atlas of Tumor Pathology: third series, Fascicle 17 Tumors of the Salivary Glands. AFIP, Washington DC, 1996: 155-175.