Download pdf - Primitive neuroectodermal tumor of the maxillary …...Panoramic radiograph shows increased radiopacity in the left maxillary sinus with thinning of the innominate line of the zygomatic

Primitive neuroectodermal tumor (PNET) is a rare, high-ly malignant small round cell neoplasm that has poor pro-gnosis. PNET belongs to the Ewing’s sarcoma (ES) familyof tumors. Both PNET and ES share a common neuroec-todermal origin.1,2 However, PNET exhibits a more aggres-sive clinical behavior than ES and metastasizes very rapi-dly.3,4 The term “PNET” was first introduced by Hart andEarle5 to describe medulloblastoma-like lesions in the cere-bral hemisphere. In 1986, Dehner6 suggested differentia-tion between central and peripheral PNETs. Subsequently,PNET arising from the central nervous system was termed“central PNET (cPNET)”, while tumors developing outsidethe central and autonomic nervous systems were called“peripheral PNETs (pPNETs)”.7 PNET accounts for 1%-4% of all soft tissue neoplasms.2,8 It is more common in

children and young adults.11 PNET mostly affects the tho-racopulmonary region, pelvis, abdominal region, and ex-tremities;2,8,10,11 less frequently, it occurs in the head andneck areas.4,12,13 PNET of the maxilla is exceedingly rareamong elderly people. Only 10 cases1,8,10,11,14-19 of PNETsof the maxilla have been reported in the literature. Here,we report a case of a 67-year-old male diagnosed withPNET of the maxillary sinus after detailed clinical, radio-logical, and histopathological examinations.

Case Report

A 67-year-old man presented at a local dental clinic withpain in the left maxillary second molar tooth. His medicalhistory was unremarkable. He was diagnosed with chronicperiodontitis and underwent extraction of the affectedtooth. However, the pain continued, and 2 weeks after theextraction, he again presented with the complaint of a non-healing extraction socket. Examination revealed granula-tion tissue and debris in the extracted socket area with asso-

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Received September 24, 2013; Revised June 13, 2014; Accepted July 22, 2014*Correspondence to : Prof. Kyung-Hoe HuhDepartment of Oral and Maxillofacial Radiology, School of Dentistry, SeoulNational University, 101 Daehak-ro, Jongno-gu, Seoul 110-749, KoreaTel) 82-2-2072-3498, Fax) 82-2-744-3919, E-mail) [email protected]

Imaging Science in Dentistry 2014; 44: 307-14http://dx.doi.org/10.5624/isd.2014.44.4.307

Copyright ⓒ 2014 by Korean Academy of Oral and Maxillofacial RadiologyThis is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0)

which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Imaging Science in Dentistry∙pISSN 2233-7822 eISSN 2233-7830

Primitive neuroectodermal tumor of the maxillary sinus in an elderly male: A case report and literature review

Saiquat Shah1, Kyung-Hoe Huh2,*, Won-Jin Yi2, Min-Suk Heo2, Sam-Sun Lee2, Soon-Chul Choi2

1Department of Dental Public Health, Bangladesh Dental College, Dhaka, Bangladesh2Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea

ABSTRACT

Primitive neuroectodermal tumor (PNET), which belongs to the Ewing’s sarcoma (ES) family of tumors, is mainlyseen in children and young adults. PNETs are extremely rare in the maxilla. Here, we report a case of PNET of theleft maxillary sinus in an elderly male. Magnetic resonance imaging (MRI) revealed a slightly enhanced solid massoccupying the left maxillary sinus and infiltrating into the retroantral space. A partial maxillectomy was performed.Despite postoperative chemotherapy, follow-up computed tomography (CT) and MRI revealed a nodal metastasis inthe submandibular space. Neck dissection was performed. However, the patient died 10 months after the secondsurgery because of distant metastasis to the liver. MRI and CT were particularly useful in detecting the extent of thetumor, recurrence, and metastasis. Further, a literature review of the previously reported PNET cases of the maxillawas carried out. In this paper, we also discuss the current approach for the diagnosis and management of thesetumors. (Imaging Sci Dent 2014; 44: 307-14)

KEY WORDS: Neuroectodermal Tumors, Primitive; Maxillary Sinus; Magnetic Resonance Imaging

ciated gingivobuccal swelling. He underwent a curettageoperation. A biopsy specimen was taken. The histopatho-logical report revealed a small focal cluster of round cellsand blood clots. The patient was referred to Seoul NationalUniversity Dental Hospital for further investigation becauseof a suspicion of malignancy.

At the Seoul National University Dental Hospital, thepatient underwent thorough clinical, radiological, and his-topathological examinations. Panoramic radiography rev-

ealed generalized sclerosis of both maxillary sinuses withincreased radiopacity in the left maxillary sinus. Thinningof the innominate line of the zygomatic process of the leftmaxilla was evident (Fig. 1). Both the panoramic and pos-teroanterior skull projections showed erosion of the pos-terolateral wall of the left maxillary sinus (Fig. 2). Magne-tic resonance (MR) images revealed a solid mass presum-ably arising from and occupying the left maxillary sinuswith infiltration into the retroantral space posteriorly, andgingivobuccal sulcus inferiorly (Fig. 3). A slightly hyperin-tense T2 signal and minimal enhancement were noted. Abone scan revealed increased uptake in the left maxilla(Fig. 4).

Histologically, the tumor was composed of sheets ofsmall round to oval cells, which were arranged in lobules,separated by fibrous septa. Most cells were characterizedby ill-defined, scanty, pale-staining cytoplasm and well-defined nuclei with coarse chromatin (Fig. 5). Immuno-histochemical studies demonstrated positive immunoreac-tivity for MIC2 (CD99), neuron-specific enolase (NSE),S-100 protein, and cytokeratin (CK) (Fig. 6). The diagno-sis of PNET was made on the basis of microscopic andimmunohistochemical findings. A partial maxillectomywas performed (Fig. 7). Following the surgery, the patientreceived one cycle of chemotherapy with anti-cancer drugsvincristine and cisplatin. No additional chemotherapy wasgiven, as the overall condition of the patient was deterio-rating. Three months after the surgery, the patient was read-mitted with an enlarged left submandibular lymph node. Afollow-up computed tomographic (CT) examination reveal-ed a 2-cm mass in the left submandibular space compress-ing the submandibular gland indicating local nodal metas-tasis (Fig. 8). The lymph node metastasis exhibited mini-mal enhancement. The patient was put on a two-cycle che-

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Fig. 1. Panoramic radiograph showsincreased radiopacity in the leftmaxillary sinus with thinning of theinnominate line of the zygomaticprocess of the left maxilla.

Fig. 2. Posteroanterior skull radiograph demonstrates erosion ofthe lateral wall of the left maxillary sinus.

motherapy treatment. However, there was no response tochemotherapy. A fat-suppressed T2-weighted MR image,taken 4 months after the CT scan, revealed a marked enl-argement of the metastatic submandibular lymph node (Fig.9). Surgery was performed to eliminate the mass in theneck. The tumor was a well-encapsulated friable mass, and

its cut surface showed a gray-tan fleshy appearance withfocal areas of necrosis and hemorrhage. Microscopically,the tumor cells had small round nuclei that varied fromvesicular with inconspicuous nucleoli to stippled chroma-tin with ill-defined cell borders. There were numerousmitoses. Neither rosettes, pseudorosettes, nor neurotubules

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Saiquat Shah et al

Fig. 3. Magnetic resonance imagesreveal hyperintense T2 (A) and hy-pointense T1 signal lesion (B) withminimal enhancement occupyingleft maxillary sinus (C, D). Note theinfiltration into the retroantral spaceposteriorly, and gingivobuccal sul-cus inferiorly. The central low sig-nal intensity with a dark rim is pos-sibly due to a hematoma from theinitial curettage/surgical procedure.

A B

C D

Fig. 4. Bone scans show hot spotsin the left maxilla.

A B

were identified (Fig. 10). On the basis of these findings,the tumor was interpreted as metastatic PNET. Followingthe second surgery, the patient decided not to continue histreatment. Six months later, the patient developed distantmetastasis of tumor cells to the liver; he died 10 monthsafter the second operation.

Discussion

PNET is not a common tumor in the head-neck region.Jürgens et al4 reported 42 cases of PNETs. Of these, only4 were head-neck PNETs. None of the cases reviewed byMarina et al12 were head-neck PNETs. In their series of54 cases, Kushner et al13 found only 1 case of head-neckPNET. However, Jones and McGill11 reported that thehead-neck region was the second most common site forPNET after the thoracopulmonary region. Incidence ofPNETs in the maxilla is even rarer. Of the 11 cases studied

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Fig. 5. Photomicrograph of a histopathological slide of primarytumor shows tumor cells with round to oval outlines, arranged in alobular pattern. The nuclei are well-defined and hyperchromatic,while the cytoplasm is very scanty (H&E stain, 200×).

Fig. 6. Photomicrographs A. Tumor cells are stained positively for CD99, (CD99 stain, 200×). B. The majority of tumor cells are positivefor neuron-specific enolase (NSE stain, 200×). C. A few tumor cells are positive for S-100 protein (S-100 stain, 200×). D. Tumor cellsshow a focal positive reaction for cytokeratin (CK stain, 200×).

A B

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by Jones and McGill,11 only 1 arose in the maxilla. Wind-fuhr1 made an excellent review of 27 cases of head-neckPNETs. In the report, only 6 cases occurred in the maxilla.However, after an extensive search of the existing English-language literature, we could identify 10 reported cases ofPNETs of maxilla.1,8,10,11,14-19 The clinical presentations,imaging features, microscopic findings, treatment modali-ties, and clinical courses of these cases are presented inTable 1. PNET has been reported to occur in young people.9

One study1 reported that 85% of head-neck PNET patientswere younger than 20 years of age. Of the 10 reported casesof maxillary PNETs that we identified, 6 patients were

under the age of 20 years. We did not find any sex predilec-tion in the maxillary PNETs. This finding was consistentwith previous reports. Most of the reported cases of PNETsof the maxilla occurred either as a soft tissue mass orswelling (Table 1).

Like those of PNETs of other body parts, radiologicalfindings of head-neck PNETs were non-specific (Table1).1,8,10,11,14-19 On plain radiographs, they appeared as areasof bone destruction. On CT images, the PNETs we foundappeared as heterogeneously enhancing masses. On T1-weighted MRI, these tumors have isointense presentationto muscle, whereas on T2-weighted MRI, PNETs show aheterogeneous hyperintense signal. In our case, the rela-

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Saiquat Shah et al

Fig. 7. Panoramic radiograph rev-eals partial maxillectomy.

Fig. 8. Follow-up enhanced computed tomography (CT) image,taken 3 months after the operation, reveals a minimally enhancing2-cm mass in left submandibular space compressing the submandi-bular gland.

Fig. 9. Follow-up fat-suppressed T2-weighted MR image, takenafter 4 months after the follow-up CT scan, shows an increase insize of the metastatic lymph node in the left submandibular space.

tively low T2-weighted MR signal intensity was indicativeof a solid tumor with high cellularity. The central low sig-nal intensity was possibly due to bleeding/hematoma/he-morrhage from the initial curettage/surgical procedure.Initial histopathological reports from the left maxillarysinus also confirmed the presence of blood clot/necrotictissues. In our opinion, the lesion arose from the mucosallining of the maxillary sinus. However, we did not rule outthe bony area surrounding the maxillary sinus as the pos-sible site of origin. Once developed, the lesion infiltratedthe maxillary alveolar bone, which resulted in mobility ofthe maxillary molar tooth. After extraction of the tooth,the growth accelerated further. Minimal enhancement ofthe enlarged lymph node on the follow-up enhanced CTimage gave the impression of central necrosis. However,T2-weighted MRI demonstrated that there was no necroticportion of a markedly high signal intensity. The minimalenhancement on the enhanced CT scan might have beencaused by the high cellularity of the metastatic lymph nodeas tumors with high cellularity normally show delayedenhancement or a low degree of enhancement. Ibarburenet al17 studied the CT and MRI findings of 17 patients withperipheral PNET. They reported that both CT and MRI arevery useful in preoperative staging and in planning thesurgical approach. CT and MRI were also helpful in thedetection of recurrent and metastatic disease. We believethat MRI should be considered the imaging modality ofchoice for pre- and post-surgical assessments of PNET, asit is more effective than CT in detecting soft tissue abnor-malities and their relation to adjacent vascular and nerv-ous structures.

Due to their highly unpredictable behavior, the manage-ment of PNETs is often challenging. Thus far, no standardtreatment protocol has been developed for PNETs.1 Thecurrent approach for the management of these tumors in-cludes a combination of therapeutic modalities like earlysurgery along with multiple chemotherapy to treat theresidual disease and to prevent metastatic or recurrentdisease.1,2,11,13,20 Multi-agent chemotherapy including vin-cristine, doxorubicin, and cyclophosphamide improvessurvival without any significant morbidity.21,22 Zimmerm-man et al22 reported that chemotherapy is mandatory asthe first-stage treatment in order to avoid a mutilating sur-gical procedure and intraoperative tumor cell dissemina-tion. This treatment may be supplemented by radiotherapy,which should be given to patients who do not have a sur-gical option that restores physiology and to patients whosetumor has been excised with an inadequate margin.1 Giventhe particularly aggressive nature of PNET, effective localcontrol requires tumor-free surgical margins and wide safe-ty margins.2 However, such margins may not always beavailable in the maxilla region because of its proximity tovital structures. In the present case, the proximity of themass to the skull base prevented us from further resection.In addition, the patient’s overall weak condition kept usfrom an aggressive use of radiation therapy and multi-agentchemotherapy, which presumably accelerated the tumorgrowth and metastasis.

Although steadily improving, the prognosis of PNET isgenerally considered to be poor with a high incidence ofrapid metastasis to distant sites such as the lung, liver, andbone.1,2 The patient in the present report also developedmetastasis to the liver 6 months after the second surgery.Kimber et al20 reported that tumors arising from the headand neck, as well as from the chest, had an intermediateprognosis compared with tumors from the paraspinal andscapular areas, which were associated with a favorable out-come. Jones and McGill11 reported that 27% patients withhead-neck PNET had metastatic disease at the time of pre-sentation. In contrast, in the series of Nikitakis et al,2 allthe 5 head-neck PNET patients were alive. Only 1 patientdeveloped distant metastasis. Prognosis of PNET mainlydepends on tumor location, tumor size, presence of meta-static disease at the time of initial diagnosis, and responseto initial chemotherapy. The reported 3-year survival rateis about 50%.2-4,8 Survival in the study of Mendel et al23

was an average of 27.3 months for asymptomatic patientsand 15.2 months for symptomatic patients from the timeof initial diagnosis. In the cases of maxillary PNET we re-viewed,1,8,10,11,14-19 elderly patients seemed to have a rela-

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Fig. 10. Photomicrograph of histopathological slide of the metastat-ic tumor, reveals tumor cells with round nuclei and ill-defined cyto-plasm. Numerous mitoses are observed (H&E stain, 200×).

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Saiquat Shah et alTa

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tively poor prognosis compared with their younger coun-terparts although only 3 patients had undergone follow-upfor 3 years at the time of the study.

PNET is a very aggressive malignancy with a poor sur-vival rate. It should be included in the differential diagno-sis of fast-growing soft tumors, particularly those that haveimaging features of high cellularity.

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