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Year : 2017  |  Volume : 23  |  Issue : 2  |  Page : 141-144  

A case of retroperitoneal malignant triton tumor in a Nigerian boy

1 Department of Surgery, Paedaitric Surgery Unit, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria
2 Department of Histopathology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria
3 Department of Surgery, Division of Neurosurgery, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria

Date of Web Publication3-Oct-2017

Correspondence Address:
Jideofor Okechukwu Ugwu
Department of Surgery, Nnamdi Azikiwe University Teaching Hospital, PMB 5025, Nnewi, Anambra State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njs.NJS_57_16

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Malignant peripheral nerve sheath tumor is a rare tumor occurring in 5%–10% of all malignant soft tissues sarcomas and triton tumor arising from neurofibromatosis type 1 (NF-1) is even rarer with associated high rate of mortality. No case of triton tumor has been reported in Nigeria to the best of our knowledge. We seek to report a case of lately detected retroperitoneal triton tumor presenting in a 12-year-old Nigerian child who was brought with bilateral lower limb weaknesses, weight loss, and a right lumbar mass. There were multiple café au lait spots on the body. Abdominal computerized tomographic scan revealed a huge right retroperitoneal mass crossing the midline, compressing adjacent structures with multilevel intraspinal extensions. Core needle biopsy performed and both histology and immunohistochemical studies confirmed the diagnosis, but patient demised in the course of care. The aim is to heighten suspicion of this extremely very rare malignant tumor in children with NF-1.

Keywords: Nerve sheath tumors, neurofibromatosis, retroperitoneal tumors

How to cite this article:
Ugwu JO, Onwukamuche ME, Ekwunife HO, C Emejulu JK, Modekwe V, Osuigwe OA. A case of retroperitoneal malignant triton tumor in a Nigerian boy. Niger J Surg 2017;23:141-4

How to cite this URL:
Ugwu JO, Onwukamuche ME, Ekwunife HO, C Emejulu JK, Modekwe V, Osuigwe OA. A case of retroperitoneal malignant triton tumor in a Nigerian boy. Niger J Surg [serial online] 2017 [cited 2021 Sep 22];23:141-4. Available from: https://www.nigerianjsurg.com/text.asp?2017/23/2/141/215910

  Introduction Top

Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors and constitute about 5%–10% of all soft tissue sarcomas. Malignant triton tumor (MTT), a variant of MPNST with rhabdomyoblastic differentiation is extremely rare with high rate of mortality and are found in only 5% of all MPNST.[1],[2],[3] It was first described by Masson[4] as rhabdomyosarcomas in patients with neurofibromatosis type 1 (NF-1). MTT has been found to occur in patients with NF-1 in slightly more than 50% of the cases, whereas the rest are sporadic.[1],[2],[3],[5] It runs an aggressive cause with high mortality, especially those on a background of NF-1.[3]

Common sites of MTT include head, neck, extremities, and trunk whereas those occurring in the retroperitoneum, viscera, mediastinum, and intracranium are quite rare.[6] Diagnosis is confirmed by histology with immunohistochemical studies for desmin, vimentin, actin, myoglobulin, and S-100 protein.[7],[8] The main stay of treatment is complete excision where possible in addition to adjuvant radiotherapy and chemotherapy.[3],[5] There are <10 reported cases of retroperitoneal MTT in literature out of which only one was in a child. None has been reported in Nigeria to the best of our knowledge.[7] The rarity of this condition and its aggressive biological behavior and mortality has prompted us to report this case.

  Case Report Top

A 12-year-old boy was brought to the children emergency room of Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria with the complaints of bilateral thigh pains of 6 weeks and inability to walk of 2 weeks duration. There was associated the loss of sensations from the hips down to the feet, significant weight loss, and loss of urinary and anal sphincteric functions. There was no cough and both parents and patient never observed rashes nor pigmented patches on the skin.

When examined, he was found to be chronically ill-looking, severely emaciated with multiple café au lait spots on the trunk and limbs [Figure 1] and subcutaneous nodules on the upper limbs. He had a lumbar swelling that was poorly delineated, tender and hard. Power on both limbs was Grade 0 and there was a right lumbar scoliosis. The full blood counts and serum electrolytes with blood urea and creatinine assays were all within normal ranges.
Figure 1: Café au lait spots on the skin

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Abdominal computerized tomography with contrast was performed and demonstrated a huge right lumbar and paraspinal mass extending from the level of L1 vertebrae down to the pelvis measuring 17.0 cm by 11.4 cm and 10.6 cm in widest cranio-caudal, antero-posterior and transverse dimensions, respectively, compressing the inferior vena cava and displacing the abdominal aorta to the left with stretching of the left renal pedicle. There was intraspinal involvement with widening of the right neural foramina of L1/L2, L2/L3, and L3/L4 with lytic destruction of T11-L3 vertebra [Figure 2]. There were nodular lesions of varying sizes in both lungs.
Figure 2: Abdominal computerized tomographic scan

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Considering the inoperable nature of the patient due to his poor clinical status, a conservative care was adopted while an ultrasound guided core needle biopsy was carried out in the radiology suite. He was placed on analgesics, subcutaneous heparin, and prophylactic antibiotics. The histological report read malignant peripheral nerve tumor composed of alternating hypercellular and hypocellular myxoid area. These malignant cells have slightly pleomorphic hyperchromatic nuclei with scanty cytoplasm. There were areas showing rhabdomyoblastic differentiation with foci of coagulative necrosis, on immunohistochemical studies, the slides stained positive for desmin, myogenin, S-100 and negative for epithelial membrane antigen (EMA) [Figure 3] and [Figure 4]. He developed breathlessness and died 31 days after admission.
Figure 3: (a) Photomicrograph of H and E. Tumor composed of alternating hypercellular and hypocellular myxoid area (b) malignant cells having slightly pleomorphic hyperchromatic nuclei with scanty cytoplasm. There were areas showing rhabdomyoblastic differentiation with foci of coagulative necrosis

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Figure 4: Immunohistochemical stains. (a) Epithelial membrane antigen EMA (negative) suggesting that it is not epithelial in origin. (b) Desmin (positive) suggesting rhabdomyosarcoma and other tumours with myoid differentiation. (c) Myogenin (positive), usually expressed in rhabdomysarcomas. (d) S--100 protein (positive) suggests neural origin

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  Discussion Top

MTTs are extremely rare tumors arising from the peripheral nerve sheaths and they constitute a variant of MPNST with rhabdomyoblastic differentiation.[4] There are <170 cases reported worldwide and most are case reports and case series with 9 cases as the only single largest report in literature.[6],[9],[10] Among the scanty reports of peripheral nerve sheath tumors from Sub-Saharan Africa, none was specified as MTTs.[11],[12],[13] Retroperitoneal triton tumors are even rarer and <10 have been reported in literature so far out of which only one was in a child.[6],[7]

Woodruff et al.[14] first used the word triton tumor to describe these variants of MPNSTs and developed a criteria for its diagnosis which includes: (1) Tumor arising from a peripheral nerve in a patient with NF-1 or location typical of MPNST, or represents a metastases from such a tumor, (2) tumors demonstrating growth characteristics of Schwann cells, (3) tumors contain rhabdomyoblasts that appear to arise from within the body of the peripheral nerve tumor and not extension from extrinsic rhabdomyosarcoma. Daimaru et al.[15] further included tumors in patients without NF-1 that are microscopically compatible with malignant schwannoma and contain focal rhabdomyoblas-ts or patients with tumors consisting of rhabdomyoblastic differentiation with focal Schwann cell elements within a nerve or in patients with NF-1. This captures both the sporadic form and those associated with NF-1.

The index patient was a 12-year-old male who presented with a short history of bilateral thigh pains, progressive weakness of both lower limbs and a large abdominal mass. This appears to be the usual progression of retroperitoneal triton tumors as in previous reports.[11],[16] Even though, the parents and the referring doctors did not observe hyperpigmented patches or nodules on the skin, these were found on examinations as shown in [Figure 1]. MTT occurring in patients with NF-1 is more common, usually more than 50% of the cases; however, there are some sporadic cases not associated with NF-1.[1],[6],[7],[8],[10],[15],[17] Some have been suggested to arise following irradiations.[6] Those associated with NF-1 have been found to occur more in younger male patients and are more aggressive as seen in the index case.[6]

Ducatman and Scheithauer[18] however reported a case of retroperitoneal MTT with NF-1 in a 12-year-old female, that again was the only report of MTT occurring in retroperitoneal space in a child as previously reported.[7],[18] Retroperitoneal MTT is a locally invasive tumor but also metastasizes to the lungs.[7],[11],[16],[19] The index case had metastasis to the lungs as picked up by the computerized tomographic scan. Imaging with computerized tomographic scan and magnetic resonance imaging could be elucidatory in terms of tumor location and extension but diagnosis is confirmed by tissue histology and immunohistochemical staining for S-100 protein, desmin, actin.[7],[17] Our patient had an abdominal computerized tomographic scan as shown in [Figure 2]. The findings of a huge retroperitoneal mass with extension into the spine, adherence to the inferior vena cava and aorta with stretching of the left renal pedicle coupled with the unstable clinical status precluded the option of operative intervention at the time. We then carried out a core needle biopsy which was strongly suggestive of triton tumor on routine hematoxylin and eosin stains and confirmed with positive immunohistochemical stains for S-100, myogenin and desmin and negative to EMA [Figure 3] and [Figure 4]. Negativity to EMA suggests that it is not epithelial in origin.[19] Core needle biopsy has been strongly suggested to give a good tissue yield for MTT.[20]

Even though there is no standardized, guideline for treatment of MTT, Surgical extirpation has been found to be the mainstay of treatment.[1],[8],[11],[17] Adjuvant chemotherapy and radiotherapy have been used with doubtful effects.[17] Despite treatments, MTT has grave outcomes with high mortalities worse with the retroperitoneal lesions, most cases die within months of diagnosis as a result of late detection, local invasion, and metastasis.[1],[6],[11],[20] This has prompted some authors to suggested that MTT be described as a different entity from MPNST because of its more aggressive tumor characteristic and attendant dismal outcome.[8]

  Conclusion Top

MTT of the retroperitoneal space is an extremely rare tumor of the nerve sheaths and none has been reported in Nigeria. It is often associated with NF-1. Perhaps, a more routine and close surveillance on these patients could aid early detection and treatment.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Weiss SW, Goldblum JR, editors. Malignant tumors of peripheral nerves. In: Enzinger and Weiss's Soft Tissue Tumors. 5th ed. China: Mosby Elsevier; 2008. p. 903-44.  Back to cited text no. 1
Brooks JS. Disorders of soft tissue. In: Sternberg SS, editor. Diagnostic Surgical Pathology. 3rd ed. Philadelphia: Lippincott Williams and Wilkins; 1999. p. 131-221.  Back to cited text no. 2
Pourtsidis A, Doganis D, Baka M, Bouhoutsou D, Varvoutsi M, Synodinou M, et al. Malignant peripheral nerve sheath tumors in children with neurofibromatosis type 1. Case Rep Oncol Med 2014;2014:843749.  Back to cited text no. 3
Masson P. Recklinghausen's neurofibromatosis, Sensory neuromas and motor neuromas. Libman Anniversary. Vol. 2. New York: The International Press; 1932. p. 793-802.  Back to cited text no. 4
Tripathy K, Mallik R, Mishra A, Misra D, Rout N, Nayak P, et al. Arare malignant triton tumor. Case Rep Neurol 2010;2:69-73.  Back to cited text no. 5
Yakulis R, Manack L, Murphy AI Jr. Postradiation malignant triton tumor. A case report and review of the literature. Arch Pathol Lab Med 1996;120:541-8.  Back to cited text no. 6
Li Z, Xiang J, Yan S, Gao F, Zheng S. Malignant triton tumor of the retroperitoneum: A case report and review of the literature. World J Surg Oncol 2012;10:96.  Back to cited text no. 7
Mae K, Kato Y, Usui K, Abe N, Tsuboi R. A case of malignant peripheral nerve sheath tumor with rhabdomyoblastic differentiation: Malignant triton tumor. Case Rep Dermatol 2013;5:373-8.  Back to cited text no. 8
Tian L, Shang HT, Bilal S, Li YP, Feng ZH, Lei DL, et al. Treatment of malignant triton tumor in zygomatic region. J Craniofac Surg 2012;23:e265-8.  Back to cited text no. 9
Brooks JS, Freeman M, Enterline HT. Malignant “Triton” tumors. Natural history and immunohistochemistry of nine new cases with literature review. Cancer 1985;55:2543-9.  Back to cited text no. 10
Nthumba PM, Juma PI. Malignant peripheral nerve sheath tumors in Africa: A clinicopathological study. ISRN Surg 2011;2011:526454.  Back to cited text no. 11
Legbo JN, Shehu BB, Malami SA. Malignant peripheral nerve sheath tumour associated with von Recklinghausen's disease: Case report. East Afr Med J 2005;82:47-9.  Back to cited text no. 12
Odebode TO, Afolayan EA, Adigun IA, Daramola OO. Clinicopathological study of neurofibromatosis type 1: An experience in Nigeria. Int J Dermatol 2005;44:116-20.  Back to cited text no. 13
Woodruff JM, Chernik NL, Smith MC, Millett WB, Foote FW Jr. Peripheral nerve tumors with rhabdomyosarcomatous differentiation (malignant “Triton” tumors). Cancer 1973;32:426-39.  Back to cited text no. 14
Daimaru Y, Hashimoto H, Enjoji M. Malignant “triton” tumors: A clinicopathologic and immunohistochemical study of nine cases. Hum Pathol 1984;15:768-78.  Back to cited text no. 15
Hoshimoto S, Morise Z, Takeura C, Ikeda M, Kagawa T, Tanahashi Y, et al. Malignant Triton tumor in the retroperitoneal space associated with neurofibromatosis type 1: A case study. Rare Tumors 2009;1:e27.  Back to cited text no. 16
Mijović Ž, Mihailović D, Živković N, Kostov M, Živković S, Stojanović N. A rare case of retroperitoneal malignant Triton tumor invading renal vein and small intestine. Vojnosanit Pregl 2013;70:322-5.  Back to cited text no. 17
Ducatman BS, Scheithauer BW. Malignant peripheral nerve sheath tumors with divergent differentiation. Cancer 1984;54:1049-57.  Back to cited text no. 18
Pinkus GS, Kurtin PJ. Epithelial membrane antigen – A diagnostic discriminant in surgical pathology: Immunohistochemical profile in epithelial, mesenchymal and haematopoietic neoplasm using paraffin section and monoclonal antibodies. Hum Pathol 1985;16:929-40.  Back to cited text no. 19
Radovanovic D, Vukotic-Maletic V, Stojanovic D, Lalosevic DJ, Likic I, Stojsic Z, et al. Retroperitoneal “Triton” tumor. Hepatogastroenterology 2008;55:527-30.  Back to cited text no. 20


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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