Pediatr Radiol (2004) 34: 1005–1007 DOI 10.1007/s00247-004-1286-5
Ensar Yekeler Memduh Dursun Feryal Gun Huseyin Kilincaslan Adem Ucar Hakan Genchellac Gulden Acunas
Received: 29 April 2004 Revised: 1 June 2004 Accepted: 15 June 2004 Published online: 24 July 2004 Springer-Verlag 2004
E. Yekeler (&) Æ M. Dursun Æ A. Ucar H. Genchellac Æ G. Acunas Department of Radiology, Istanbul Faculty of Medicine, Millet caddesi Capa, Istanbul, 90, Turkey E-mail:
[email protected] Tel.: +90-212-5337505 Fax: +90-212-6310728 F. Gun Æ H. Kilincaslan Department of Paediatric Surgery, Istanbul Faculty of Medicine, Istanbul, Turkey
CASE REPORT
Sialoblastoma: MRI findings
Abstract Sialoblastoma is a rare, aggressive and potentially malignant salivary gland tumour diagnosed in the neonatal period. A total of 28 cases have been reported in the literature, but reports of the imaging findings are limited. We describe a neonate with a right parotid sialoblastoma. MRI showed a large facial mass, which was mostly hypointense to the brain on T1-weighted images and mildly hyperintense on T2weighted images. There were foci of haemorrhage and necrosis. Heterogeneous and weak contrast enhancement was detected on contrast-enhanced images. The tumour
Introduction Tumours that originate in salivary gland ductal or secretory epithelial cells are exceedingly rare in children less than 2 years of age [1]. Sialoblastoma is a rare, aggressive and potentially malignant salivary tumour occurring in the neonatal period. A total of 28 cases have been reported in the literature, the clinical and histopathological features being the focus of the reports [2–6]. We describe the MRI findings of a huge sialoblastoma originating from the right parotid gland.
Case report A boy weighing 3,200 g was born spontaneously at term by vaginal route in an outside hospital. His antenatal US records were not available. The presence of a right-sided
invaded the maxilla and adjacent muscles.
Keywords Salivary gland Æ Neoplasm Æ Sialoblastoma Æ MRI Æ Child
facial mass prompted referral to our hospital. Physical examination revealed a 15·10·10-cm soft-tissue mass, mostly covered by skin, but with some superficial necrotic areas. Routine laboratory data were normal. MRI revealed a facial mass located in the region of the right parotid gland and invading the maxilla and adjacent muscles. The mass included some areas of haemorrhage and necrosis (Fig. 1). Heterogeneous and weak contrast enhancement was detected on contrastenhanced images (Fig. 1d). Enlarged regional lymph nodes were not detected. Histological examination of a wedge resection revealed the diagnosis of sialoblastoma. Based on the MRI findings, the mass was not suitable for total resection, but subtotal resection was attempted. The mass was necrotic and fragile and found to extend through the adjacent muscles to the right maxilla and oropharyngeal mucosa; the right parotid gland could not be discerned separately from the mass. The orbit was
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Fig. 1 MRI. T1-weighted (T1W) a axial and b coronal images show a huge facial mass mostly hypointense to the brain with some hyperintense haemorrhagic areas. c T2-W image reveals mild hyperintensity of the lesion. Notice that the hyperintense region seen on the T1-W image (b) is very dark on the T2-W image (c), suggesting haemorrhage in the deoxyhaemoglobin phase. Extension of the tumour to the maxillary region is seen (arrow). d Contrast-enhanced T1-W image shows minimal heterogeneous contrast enhancement and hypointense necrotic areas
not invaded. Macroscopic evaluation of the mass showed the right parotid gland to be completely replaced by tumour. Residual tumour was treated with a regimen which included vincristine, actinomycin D and cyclophosphamide (VAC). Follow-up MRI demonstrated shrinkage of the mass leaving a small residual tumour mass or granulation tissue. After 8 months, there has been no increase in the size of the residual soft-tissue mass.
Discussion Salivary gland tumours have been reported under a variety of names such as congenital basal cell adenoma, basal cell adenoma, basaloid adenocarcinoma and
congenital hybrid basal cell adenoma-adenoid cystic carcinoma. In 1966, Vawter and Tefft [7] suggested the term ‘embryoma’ for this unique neonatal tumour. In 1988, Taylor [8] suggested the term ‘sialoblastoma’. Most of the sialoblastomas reported have arisen in the parotid gland, the remainder in the submandibular gland. The majority of the tumours have been in neonates, although one tumour in a 21-month-old child has also been reported [9]. Sialoblastomas are composed of epithelial cells, which may be basaloid with scanty cytoplasm, round-tooval nuclei with single or few nucleoli and a relatively fine chromatin pattern, or more mature cuboidal epithelial cells with pink cytoplasm. Surgical excision is the primary treatment of choice. Local recurrence or persistence is not uncommon [7, 10, 11]. Sialoblastomas
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may become more anaplastic over time, and this histological change may predict local recurrence and possibly the risk of distant metastases. In the presence of persistent or locally recurrent tumour, chemotherapy or radiotherapy can be used to prevent distant spread [7, 10, 11]. Imaging features of sialoblastoma have been documented in a limited number of cases [9, 12]. The CT appearance is of a soft-tissue mass hypodense to the brain and isodense to muscle. Som et al. [9] detected low–intermediate signal intensity and slightly higher intermediate signal intensity on T1-weighted (T1-W) and
T2-weighted (T2-W) images, respectively. In our case, the greater part of the lesion excluding necrotic and haemorrhagic areas was mildly hyperintense on T2-W images, which was lower than that described by Som et al. [9] The finding of mild hyperintensity on T2-W images suggests a high nucleus/cytoplasmic ratio belonging to blastema and can be predictive for the diagnosis of blastomas. In the current case, the cause of intralesional haemorrhage on MRI was unclear. It could have occurred spontaneously into the fragile tumour tissue or have resulted from minor trauma during vaginal delivery.
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