Intracranial primary synovial sarcoma mimicking a spontaneous cerebral hematoma-a case report and review of the literature

BACKGROUND

Synovial sarcoma is a soft tissue sarcoma, of uncertain histological origin, usually located near large joints and concerning mainly young adults. Intracranial presentation in the form of metastasis from a primitive body sarcoma has been rarely reported. However, intracranial primitive synovial sarcoma (IPSS) is extremely rare and only a few cases have been reported in the literature.

CASE DESCRIPTION

We present the case of a 48-year-old man, with no particular medical history, that was referred to our hospital for severe headache with a normal neurological exam and a CT cerebral scan showing a left frontal lobe hematoma. The initial cerebral CT scan didn't show any vascular malformation and the body CT scan was negative for a primitive lesion. A close follow-up with a cerebral MRI three months later, demonstrated a T1 enhanced lesion with an important volume progression. The patient underwent a complete surgical removal of this lesion and the first pathology diagnosis was compatible with a meningioma. After further proofreading by an expert and molecular analysis, the diagnosis of monophasic synovial sarcoma was confirmed. Nine months after the first surgery, the follow-up MRI showed the progressive recurrence of the lesion and in this context the patient underwent a second surgery with total resection of the tumor and frontal thin margin excision. Afterwards, the patient was treated with adjuvant radiotherapy, with a good clinical evolution, and till now the follow-up shows no recurrence.

CONCLUSION

IPSS is an extremely rare sarcoma, with challenging diagnosis and difficult management. Specific molecular analysis is necessary. Complete resection followed by radiotherapy seem to be the most appropriate therapeutic approach. However, the prognosis is still poor. Our case is even rarer because of the initial presentation as a cerebral hematoma.

From Vesalius to tractography

The description of an anatomical specimen may look straightforward, but it appears that it depends in fact on several intermingled factors: technical methods for conservation, dissection and vascular injection and the anatomist skills are of course important. This is especially true when the studied organ, as for instance the brain, is subject to rapid putrefaction after death without any preservation technique. Nevertheless the possibility to reject, or at least criticize, the dominant paradigm is probably as important as these technical considerations: important changes occurred in brain representation between the early Middle Ages and the Early Modern Times, without major improvements of cadaveric preservation or dissection methods; Vesalius rejected the existence of the rete mirabile in human not only because he was a talented anatomist but also because he accepted and had the courage to fight the dominant tradition inherited from Galen. Such difficulties in the scientific approach obviously remain vivid, and should not be forgotten despite the development of modern tools for studying brain morphology and function.

Radionecrosis of malignant glioma and cerebral metastasis: a diagnostic challenge in MRI

Detecting a new area of contrast-enhancement at MRI after irradiation of malignant brain tumor arises the problem of differential diagnosis between tumor recurrence and radiation necrosis induced by the treatment. The challenge for imaging is to distinguish the two diagnoses given: the prognostic and therapeutic issues. Various criteria have been proposed in the literature based on morphological, functional or metabolic MRI. The purpose of this study was to perform an analysis of these tools to identify MRI best criteria to differentiate radiation necrosis lesions from malignant gliomas and brain metastases recurrence. For gliomas, the morphology of the contrast-enhancement cannot guide the diagnosis and the use of perfusion techniques and spectroscopy (multivoxels if possible) are necessary. In the follow-up of metastasis, a transient increase and moderate lesion volume is possible with a good prognosis. Morphological characteristics (volume ratio T2/T1Gd) and perfusion analysis provide valuable tools for approaching the diagnosis of radionecrosis.

Cerebral functional asymmetry and phonological performance in dyslexic adults

Developmental dyslexia is a frequent language-based learning disorder characterized by difficulty in reading. The predominant etiologic view postulates that reading impairment is related to phonological and orthographic dysfunction. The aim of this fMRI study was to evaluate the neural bases of phonological processing impairment in remediated dyslexic adults (DD). We used a rhyming words judgment task contrasted with an unreadable fonts font-matching judgment task to compare patterns of activation and functional asymmetry in DD and normal-reading young adults. We found evidence of a link between asymmetry in inferior frontal gyrus and performance during the phonological processing. We also observed that DD recruit a network including regions involved in articulatory control in order to achieve rhyme judgment suggesting that, due to a lack of hemispheric specialization, DD recruit the latter network to achieve rhyme judgment.

Influence of age on the dynamics of fMRI activations during a semantic fluency task

PURPOSE

Age-related fMRI changes have not been extensively studied for language, whereas important adaptive mechanisms have been seen in other cognitive fields. This study examined age-related changes in fMRI activation during language tasks and, in particular, their dynamic course.

PATIENTS AND METHODS

fMRI was performed on 22 young and 21 old healthy right-handed subjects during a silent category word-generation task. Activation and dynamics of BOLD signals were studied separately during the first and second portions of each 30-s block.

RESULTS

Activation of the left frontal lobe was initially similar in young and old participants; however, it decreased after 30 s in the old participants. On the other hand, additional areas were initially involved only in old subjects and especially in the default mode network.

CONCLUSION

This study showed age-related differences in the dynamics of fMRI activation during a silent word-generation task, suggesting a different pattern of language function with aging.

Acquisition and interactive 3D exploration of the internal structure of a dissected specimen

We present a system to keep track of a destructive process such as a medical specimen dissection, from data acquisition to interactive and immersive visualization, in order to build ground truth models. Acquisition is a two-step process, first involving a 3D laser scanner to get a 3D surface, and then a high resolution camera for capturing the texture. This acquisition process is repeated at each step of the dissection, depending on the expected accuracy and the specific objects to be studied. Thanks to fiducial markers, surfaces are registered on each others. Experts can then explore data using interaction hardware in an immersive 3D visualization. An interactive labeling tool is provided to the anatomist, in order to identify regions of interest on each acquired surface. 3D objects can then be reconstructed according to the selected surfaces. We aim to produce ground truths which for instance can be used to validate data acquired with MRI. The system is applied to the specific case of white fibers reconstruction in the human brain.

[Abnormal features of the sub renal portion of the inferior vena cava]

AIM

to determine the frequency of the abnormal anatomical features affecting the inferior vena cava (IVC).

MATERIAL AND METHODS

we performed 161 dissections of the ICV on fresh (145) or formaldehyde-injected (16) cadavers. There were 86 men and 75 women.

RESULTS

we found two abnormalities of the IVC: one left IVC in a woman and one double IVC in a man. These malformations can be explained by the embryology of the IVC.

DISCUSSION

the frequency of abnormalities of the IVC is highly variable according to the studies: Richardson (1983) found 3% for the duplication of the IVC. Other malformations have been reported: double IVC, left IVC or right IVC with azygos prolongation. We never observed such associations in our study. Left IVC could be explained by the development of the left supra-cardinal vein and by that of the left sub-cardinal and intercardinal anastomoses. Double IVC corresponds either to the development of the left supra-cardinal vein or to the persistence of the left cardinal vein or the left sub-cardinal vein.

CONCLUSION

abnormalities of the ICV dysplay different anatomical features due to the complexity of the embryogenesis of this vessel; their frequency is far from being rare. Unknowing these abnormalities could lead to severe haemorrhages during surgical interventions on the retroperitoneal, cardiac or oesophageal regions.

[Spasmodic torticollis caused by metoclopramide: a rare etiology of C1-C2 rotatory pseudoluxation in children]

Torticollis in children must always instigate a search for trauma. Many other etiologies can be found. The authors report a case of postmedicinal atlantoaxial rotatory pseudoluxation (AARP) occurring in a child. This child had fallen down in the morning with head trauma followed by headache. Clinically, a stiff neck with an irreducible right rotation of his neck, and an osteotendinous hyperreflexia were noted. There was a C1-C2 rotatory dislocation with no traumatic lesion on the cervical CT scan. After a few hours, the torticollis spontaneously reduced and then reappeared on the left side. This clinical fluctuation and the absorption of metoclopramide (Primpéran) started in the morning for acute gastroenteritis provided the diagnosis of AARP. This entity was confirmed by the good clinical and radiological follow-up and was caused by the substantial ligament laxity of the craniovertebral junction encountered in children. The analysis of medical imaging and the systematic search for a medicinal cause helped make the right diagnosis.

[Duplication of the inferior vena cava: anatomical dissection and clinical implications]

The duplication of the inferior vena cava is often incidentally discovered during radiological studies. The presence of this anomaly can be mistaken for retroperitoneal adenopathy. Its knowledge allows to avoid hemorrhagic complications during retroperitoneal surgery. An anatomical dissection of a duplication of the inferior vena cava is presented. Embryogenesis and variations are described. Radiological and clinical implications are discussed.

The persistent left superior vena cava: anatomical study, pathogenesis and clinical considerations

The persistence of a left superior vena cava (LSVC) is an intrinsically cardiac anomaly, which can lead to serious complications during catheterization via the subclavian or internal jugular vein. We found this anomaly during dissection associated with an abnormal origin of the vertebral artery originating from the aortic arch between the left common carotid and subclavian arteries. The LSVC coursed towards the right atrium through a very dilated coronary sinus ostium. No abnormality of the azygos system was found. A thorough anatomic description was then made with external and internal morphology. The embryonic development and variations are described. Radiological and clinical implications are discussed.

Anatomical study of the length of the human intestine

Although preoperative assessment of the length of the intestine may be of interest to avoid postoperative consequences of large intestinal resection, measurements of the intestine are quite rare and results variable in the literature. This anatomical study aimed to assess the length of the different intestinal segments, their variation and their correlation with sex, age, weight and height. Two hundred non-fixed adult cadavers (100 men, 100 women) who willingly gave their bodies for scientific purposes were studied. The post mortem average length of the whole intestine was 795.5+/-129 cm and was significantly longer in men and in young subjects. It was correlated with the subject's weight but not height. Multivariate analysis demonstrated that the factor showing the strongest correlation with intestinal length was body weight. This latter parameter may be useful in the preoperative assessment of intestinal length.

[Anatomical variations of the brachial plexus]

Important variations exist in the brachial plexus (Kaufmann, Cunningham, Kerr, Lee). Perivascular techniques of brachial plexus block used sometimes use important quantities of anaesthesia product. It seems that certain surgical treatment failures of brachial plexus lesions are related to the brachial plexus variations (Bonnel). Our aim is to study the brachial plexus variations and its relations from the cervical region to brachial region. We dissected twenty-three brachial plexus (13 women and 10 men, fresh or injected by formalin). We studied the brachial plexus anatomic variations and its relations. We found the anatomic variations at the level of different parts of brachial plexus: Trunk: 8 cases (34.8%); Terminal branch: 8 cases (34.8%); brachial plexus tract: 1 case (4.3%); collateral branch: 1 case (4.3%); in 5 cases we didn't find any abnormalities. Some studies show the frequency of 4th cervical root (C4) participation in brachial plexus. Kerr found 65.9%. It was 30.4% of C4 participation in brachial plexus in our series. Among the 8 cases of terminal branch variations in our series, two (8.7%) musculocutaneous was low source. The brachial plexus variations could fail the brachial plexus loco-regional anaesthesia. In the surgical treatment of brachial plexus lesions, the surgeon must know brachial plexus anatomical variations perfectly.

[Role of high-dose chemotherapy with hemopoietic stem-cell support in the treatment of adult patients with high-grade glioma]

Despite surgery, post-operative irradiation and adjuvant conventional chemotherapy, prognosis of high-grade gliomas remains poor. Carmustine (BCNU) has been shown to have limited activity at conventional dosage but is still the standard chemotherapy. Activity of chemotherapy is limited by the blood-brain barrier impermeability and high levels of expression of multidrug resistance proteins on tumor and/or endothelial cells. Despite high response rates, development of intra-arterial chemotherapy remains limited because of frequent acute brain toxicity related to drug administration. High-dose intravenous chemotherapy rescued by autologous hemopoietic stem cell transplantation is an alternative that might increase drug delivery through the blood-brain barrier and tumor control. Several phase I-II trials using high-dose BCNU were published. The maximum tolerated dose seems to be 800 mg/m2 and interstitial pneumonitis and hepatitis are dose-limiting toxicities. Few phase I-II trials of high-dose therapy were published using drug combinations. High response rates in patients with progressive tumor were observed and in adjuvant setting, encouraging results in terms of median survival time and long survivors were published. No phase III trial was reported to date. Future investigations should include randomized trials comparing high-dose and conventional-dose chemotherapy and development of new high-dose regimens that incorporate new drugs such as temozolomide.

Microanatomy of the pericallosal arterial complex

OBJECT

The pericallosal arterial complex supplies the callosal and pericallosal regions, as well as the anterior two thirds of the medial and superomedial aspects of both hemispheres. It is composed of the pericallosal artery (that is, the segment of the anterior cerebral artery located distal to the anterior communicating artery [ACoA]) and the median callosal artery (or third pericallosal artery), which originates from the ACoA. This system was studied in 46 specimens (23 human cadaver heads) injected with colored latex.

METHODS

After being injected with colored latex, embalmed, and bleached, the specimens were studied with the aid of optic magnification. The pericallosal artery was found to be divided into four segments (A2-A5 in the proximodistal direction). After giving rise to central, callosal, and cortical branches, it terminated near the splenium of the corpus callosum as the posterior pericallosal artery, or on the precuneus as the inferomedial parietal artery.

CONCLUSIONS

The authors propose a logical classification of the different variations in the pericallosal arterial complex based on embryological development. This complex can be considered a hemodynamic solution to an abnormal regression of one of its parts, which is balanced by the development of supplemental channels from other parts.

[MRI diagnosis of cavernous sinus invasion by pituitary adenomas]

Several MRI signs are helpful for the preoperative MRI diagnosis of cavernous sinus invasion by an adenoma. The first step is to analyse the percentage of encasement of the intracavernous ICA by the adenoma. If this percentage is greater than or equal to 66%, the cavernous sinus is invaded. If the percentage of encasement of intracavernous CA is less than 25%, the cavernous sinus is not invaded. If the percentage of encasement is between 25 and 66%, the analysis of the cavernous venous compartment, the drawing of intercarotid lines and the analysis of the shape and venous compartments of the cavernous sinus are necessary. The cavernous sinus invasion remains very likely if the carotid sulcus venous compartment is obliterated, or if the lateral intercarotid line is crossed. Conversely, if the median intercarotid line is uncrossed, the superior venous compartment is visible, the cavernous sinus is of normal size, or there is no bulging of its lateral dural wall, invasion of the cavernous sinus space can reliably be excluded.

Cavernous sinus invasion by pituitary adenoma: MR imaging

PURPOSE

To define magnetic resonance (MR) imaging criteria for the diagnosis of cavernous sinus invasion by pituitary adenoma.

MATERIALS AND METHODS

The MR images obtained in 106 patients (86 female, 20 male; age range, 16-71 years) were reviewed retrospectively by two physicians. The standard-of-reference criteria for invasion were the surgical findings. A chi(2) analysis was performed, and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for nine groups of MR imaging signs were computed.

RESULTS

Invasion of the cavernous sinus was certain (PPV, 100%) if the percentage of encasement of the internal carotid artery (ICA) by tumor was 67% or greater. It was highly probable if the carotid sulcus venous compartment was not depicted (PPV, 95%) or the line joining the lateral wall of the intracavernous and supracavernous ICAs was passed by the tumor (PPV, 85%). It was definitely not invaded (NPV, 100%) if the percentage of encasement of the intracavernous ICA was lower than 25% or the line joining the medial wall of the intracavernous and supracavernous ICAs was not passed by the tumor.

CONCLUSION

The radiologic diagnosis of cavernous sinus invasion by pituitary adenoma remains difficult, but the above-mentioned criteria may be of assistance.

[Cerebro-meningeal hemorrhage secondary to ruptured vascular malformation during pregnancy and post-partum]

Thirty two new cases of vascular malformations discovered during pregnancy were reviewed in a multicentric retrospective study and compared to the literature. The authors studied both the influence of pregnancy and post-partum on cerebral vascular malformations and the corresponding neurosurgical and obstetrical management. The relative frequencies of arteriovenous malformations (AVMs) and arterial aneurysms (AAs) is the same for pregnant and non-pregnant women. Pregnancy does not increase the risk of first bleeding of vascular malformations but the risk of re-bleeding is increased for AVMs. The bleeding of a vascular malformation is more strongly correlated to age than to parity. The mean maternal age at the time of rupture is greater for AAs than for AVMs, as it is in the general population. The bleeding of a vascular malformations occurs more frequently during the second and third trimesters of pregnancy than in the first one and in the post-partum. Labor and delivery are not great-risk-periods. Management of vascular malformation in pregnant woman is proposed as follow : --a ruptured AA or AVM is managed as it is in non-pregnant woman, whatever the gestational age; no fetal extraction needs to be performed except ed if the rupture occurs at the very end of the pregnancy;--an non-ruptured AVM discovered during pregnancy is treated after delivery; an non-ruptured AVM that never bled before pregnancy is managed in the same way that an non-ruptured AA.

[Pituitary disorders in pregnancy]

During pregnancy there is a normal increase in the volume of the anterior pituitary as demonstrated by MRI and hormone secretions which increase (PRL) or decrease (FSH, LH). During pregnancy pituitary adenomas, especially prolactinomas, may evolve as in non-pregnant women (microadenomas) or differently (macroadenomas). In 35 % of cases macroprolactinomas worsen during pregnancy making their medico-surgical management mandatory prior to pregnancy. Inversely, pregnancy occurring in a subject with a microprolactinoma never induces severe local complications so such tumors may be managed surgically or medically. Surgery should be performed for acromegaly or Cushing's disease before or early in pregnancy. Subacute pituitary apoplexy (intratumoral hemorrhage) occurs in about 10 to 15 % of adenomas but, generally speaking, clinical symptoms remain mild in pregnant women. Lymphocytic hypophysitis occurs at the end of pregnancy, or during the post-partum period. The association of complete pan-hypopituitarism and hypersignal on MRI examination may mimic hypophyseal apoplexy and could lead to and inappropriate surgical procedure.

[Development of the corpus callosum (CC)]

Corpus callosum embryology can be divided into three parts: during "commissuration", a cellular mass develops between the two telencephalic vesicles. The primitive lamina terminalis corresponds to the closing point of the anterior neuropore. Its dorsal part grows and forms the lamina reunions (6-8 intra uterine weeks, IUW). From ventral to dorsal, this lamina reunions gives rise to the area praecommissuralis (origin of the anterior commissure), to the primordium hippocampi (10 I.U.W., fornix), and to the massa commissuralis (10 S.I.U., corpus callosum). Fibers arising from the developing hemispheres run through this primitive corpus callosum. The growth of the corpus callosum follows the expansion of the hemispheres, in a rostro-caudal and then dorso-ventral circular movement. The last part of the corpus callosum to form is the rostrum. Maturation occurs postnatally, and corresponds to axonal elimination, and myelination, progressively changing the callosal connection pattern of the newborn and infant into the adult pattern.

[Morphologic anatomy of the corpus callosum]

The corpus callosum is a neopallial commissure. In inferior vertebrates, the pallial commissures are essentially represented by the anterior commissure. The corpus callosum appears in mammals only. Eutherians alone have a corpus callosum, the other mammals have an anterior commissure and hipocampal commissure. In humans, the different portions of the corps callosum are described on a median sagittal slice: rostrum, genu, body, isthmus, splenium. Klingler method allows to dissect fibers of each of these portions and their relationship with the corona radiata and optic radiations. These latter are separated from the ventricular ependyme by callosal radiations. Finally, each part of the corpus callosum participates in lateral ventricle wall formation.

[Arterial and venous vascularization of the corpus callosum]

Blood supply of the corpus callosum is assured by two arterial systems, the carotid system mainly and the vertebrobasilar system accessorily. The carotid system intervenes via the pericallosal artery, portion of the anterior cerebral artery distal to the anterior communicating artery. This pericallosal artery can be bihemispheric in 4 to 12% of the cases or azygos in 0.26% of cases. In 20 to 80% of cases, the median callosal artery arises from the communicating artery. The vertebrobasilar system intervenes in splenium vascularization by its terminal branches. These two carotid and vertebrobasilar systems give rise to perforating arteries that assure intrinsic vascularization of the corpus callosum creating a system of regular vascular stitches around the fibers of the corpus callosum. The venous drainage of the corpus callosum is essentially via callosal veins and callosocingulate veins towards the deep venous system of the brain.

Microanatomy of the hypophyseal fossa boundaries

OBJECT

The authors studied the heads of 17 adult cadavers and one fetus to clarify the anatomy of the sellar region, particularly the lateral boundaries of the hypophyseal fossa.

METHODS

Vascular injections and microdissection or histological techniques were used in this study. The roof of the cavernous sinuses and diaphragma sellae were part of a single horizontal dural layer that joined the two anterior petroclinoid folds. Laterally, the direction of this layer changed; it became the lateral wall of the cavernous sinus and joined the dura mater of the middle cerebral fossa. On the midline, this layer ballooned toward the sella through the diaphragmatic foramina, created a dural bag containing the hypophysis, and attached to the inferior aspect of the diaphragma sellae. As a consequence, no straight sagittal dural wall existed between the pituitary gland and cavernous sinus; the lateral border of the hypophyseal fossa was part of this anteroposterior and superoinferior convex bag. The authors stress the importance of the venous elements of the region and discuss the structure of the cavernous and coronary sinuses.

CONCLUSIONS

Invasion of the cavernous sinus makes surgery more risky and difficult and may necessitate modification of the surgical treatment plan. The preoperative diagnosis of cavernous sinus invasion is thus of great interest, but the possibility of normal lateral expansions of the pituitary gland must be kept in mind. A lateral expansion of this gland into the cavernous sinus was encountered in 29% of the specimens, and an adenoma that developed in such an expansion could easily mimic cavernous sinus invasion.

[MRI diagnosis of sinus cavernous invasion by pituitary adenomas]

PURPOSE

To evaluate the preoperative MRI criteria of a sinus cavernous invasion by a pituitary adenoma.

MATERIAL AND METHODS

Study of 102 cavernous sinuses among 51 patients who had had a surgical cure of pituitary adenoma. Thirteen patients had a surgical invasion of the cavernous sinus.

RESULTS

A certain number of signs eliminated cavernous sinus invasion. The best means consisted in not crossing the intercarotid line (Sensitivity-Se = 100%, Specificity-Sp = 85% and Negative Predictive Value-NPV = 100%). The others means implied: not going past twelve o'clock on the internal carotid artery-ICA (NPV = 97.1%), symmetrical size of the cavernous sinus (NPV = 92.5%), non-convexity of the lateral wall (NPV = 90.2%), visualization of at least two venous groups of the laterosellar space (NPV = 90.2%) and finally, non-displacement of the ICA (NPV = 89.2%). The best criteria for diagnosis were passing by the intra and supracavernous ICA lateral tangent (Se = 84.6%, Sp = 95%) and the percentage of ICA encasement by the adenoma exceeding 25% (Se = 92.3%, Sp = 85%).

CONCLUSION

Except the total encasement of the intracavernous ICA, the cavernous sinus can be invaded when the lateral tangent of the supra and the intracavernous ICA is crossed, and also when the percentage of ICA encasement exceeds 25%.

A new concept in Dorello's canal microanatomy: the petroclival venous confluence

The so-called Dorello's canal was studied in 32 specimens (16 human cadaver heads) injected with colored latex and fixed in formalin (28 specimens) or studied with microscopic and ultrastructural methods (four specimens). To avoid the differences usually encountered in the description of this area, the authors preferred to consider a larger space that they have named the petroclival venous confluence (PVC). It was located between two dural layers: inner (or cerebral) and outer (or osteoperiosteal). The PVC was quadrangular on transverse section. The posterior petroclinoid fold and the axial plane below the dural foramen of the abducent nerve (sixth cranial nerve) limited the PVC at the top and bottom, respectively. Its anteroinferior limit was the posterosuperior aspect of the upper clivus and outer layer of the dura mater. Its anterior limit was the vertical plane containing the posterior petroclinoid fold, and its posterior limit was the inner layer of the dura. The PVC was limited laterally by the medial aspect of the petrous bone apex and medially by the virtual sagittal plane extending the medial limit of the inferior petrosal sinus upward. The PVC was a venous space bordered by endothelium and continuous with the cavernous sinus, the basal sinus of the clivus, and the inferior petrosal sinus. There were trabeculations between the two dural layers. The petrosphenoidal ligament of Gruber may be regarded as a larger trabeculation, and it divided the PVC into a superior and an inferior compartment. The abducent nerve generally ran through the inferior compartment, where it was fixed to the surrounding dura mater. This nerve was only separated from venous blood by a meningeal sheath of varying thinness lined with endothelium. The clinical implications of these findings are discussed.

Fronto-orbital sphenoidal fibrous dysplasia

We report the clinical, radiological, and histological features of an 8-year-old boy with an unusual presentation of fronto-orbital sphenoidal fibrous dysplasia. The various forms of fibrous dysplasia are outlined and the differential diagnosis discussed. An approach to surgical management is proposed.