Case Report Acta Medica Anatolia Volume 3 Issue 3 2015 A rare and unusual case of acinic cell carcinoma of parotid gland evaluated by F-18 FDG PET/CT Billur Caliskan1, Ayse Nurdan Korkmaz1, Robert Henderson2 1Department of Nuclear Medicine, Abant Izzet Baysal University Faculty of Medicine, Bolu, Turkey 2Department of Radiology, Division of Nuclear Medicine, Keck School of Medicine University of Southern California, USA Abstract Acinic Cell Carcinoma (ACC) is a rare parotid gland tumor. In this case, we present F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) images of a 75 year old male with a history of metastatic ACC. The patient was iniatially diagnosed in 2009 after he received multiple surgeries secondary to local recurrences. The patient was also treated with chemoradiation. PET/CT was performed as part of the treatment strategy evaluation. PET/CT demonstrated brain metastasis, multiple pulmonary metastatic nodules, multiple hepatic metastasis, hilar, pleural and mesenteric masses and multiple osseous metastasis. Although ACC is a low grade malignancy, it has a tendency to recur and metastasize. In this case, we report diffuse metastatic disease of ACC. Hence, we conclude PET/CT could be a very valuable tool managing the disease. Keywords: FDG PET/CT, acinic cell carcinoma, parotid gland. Received: 14.08.2014 Accepted: 29.08.2014 doi: 10.15824/actamedica.46429 Introduction Acinic Cell Carcinoma (ACC) is a rare malignant epi- thelial tumor accounting for about 1–6% of all salivary gland neoplasms. Although it is generally known as a low grade malignancy, ACC has a tendency to recur and metastasize. Local recurrence has been reported in 8 to 56 % of the patients (1) and distant metastasis has been reported to bone, lung and brain. There is limited data about imaging modalities regarding ACC. Figure 1: Axial CT (a), PET/CT fused (b) and PET only (c) im- ACC can dedifferentiate to a more aggressive form ages of brain demonstrated (arrows) left white matter lesion (2), and this form has a greater tendency for meta- just anterior to the left lateral ventricle, frontal horn, which also static disease. PET/CT can be valuable for evaluating appeared slightly metabolically active, measuring 1.7 cm with a maximum standardized uptake value (max SUV) of 5.5 . the extent of the disease and for its management. Case Discussion A 75 year old male was initially diagnosed with ACC in About 1-3% all head and neck malignant tumors arise 2009. The patient originally underwent a left radical parotidectomy in December of 2010 and then several in the salivary glands, with the majority involving the subsequent repeat surgeries secondary to local recur- parotid gland (3). ACC comprises 1-6 % of malignant rences. The patient also received radiation therapy to salivary gland tumors and it arises most commonly the left parotid gland in 2009 as well as to the L1 ver- within parotid gland (81-98 %) followed by the sub- tebrae in 2012. Brain metastasis was also diagnosed, mandibular gland (11%) and minor salivary glands he underwent resection in December 2012 and pa- (3-12%) (3,4). The histopathological appearance of thology confirmed the metastatic carcinoma consist- neoplastic cells in ACC are similar to normal acinic ent with previously diagnosed acinic cell carcinoma. cells and the diagnosis depends on the presentation He received chemotherapy and then underwent PET/ of serous acinar cell differentiation. ACC is consid- CT two months later for subsequent treatment evalu- ered a low grade salivary gland tumor with a low rate ation. PET/CT showed brain metastasis (figure 1), of recurrence and metastasis. Distant metastasis oc- multiple lung nodules, mediastinal, pleural and hilar curs in 0 to 13% of cases (5) and the most frequent masses, hepatic metastases, a mesenteric mass (fig- metastatic site includes: cervical lymph nodes, liver, ure 2), as well as the right eleventh rib and left iliac lungs, bones (most commonly the thoracic spine), bone, consistent with osseous metastases (figure 3). brain and the contralateral orbit (4-6). Correspondence: Billur Caliskan, Department of Nuclear Medicine, Bolu, Turkey. 105 E-mail: [email protected] Case Report Caliskan B et al. sis, high mitotic figures, stromal invasion and nerve involvement (8). We could not found these features in our case’s pathology report but the cases with distant metastasis had been more aggressive clinical feature and they were suspicious for high grade ACC. Although there were numerous articles about the value of PET/CT in parotid or salivary glands (9-10), none of them reported ACC in their study patients. This likely reflects the rare nature of ACC as it is the fourth malignant tumor of the salivary gland tumors, after mucoepidermoid carcinoma, adenoid cystic carcinoma and expleomorphic adenocarcinoma. Figure 2: Maximum intensity projection (a) image of PET/CT Generally, low grade salivary gland tumors tend to demonstrated extensive metastatic disease. Axial CT and PET/ be less FDG-avid but in this case we want to remind CT fused images (b) of lungs showed innumerable pulmonary that ACC could have an aggressive and metastatic nodules, mediastinal, pleural and right hilar mass. Specifically, metabolic activity of the right hilar mass was measured max form. SUV of 20.20. Anterior right mesenteric mass was measured 8.3 cm with a max SUV of 17.8 (c). There were several hyper- metabolic foci throughout the liver, the largest of which was in the lateral segment of the left hepatic lobe (segment 2) with a max SUV of 9.5 (d). In the presented, case we observed brain, lung, liver, mediastinal and mesenteric nodal disease and bone metastasis. The patient had a prior history of L1 me- tastasis with subsequent radiation therapy to this region. So although bone metastasis was observed on rib and iliac bone on FDG PET/CT we could not Figure 3: Sagittal CT (a), fused PET/CT (b) and PET (c) images show L1 metastasis. There were only three cases in showed hypermetabolic focus within the right eleventh rib, and the literature with spinal metastasis and our case is also axial images of CT (d), fused PET/CT (e) and PET (f) images showed hypermetabolic lesion (arrows) within the left ilium the forth (3,4,6). consistent with osseous metastatic disease. To our knowledge there is limited data regarding Conclusion imaging modalities of ACC. Cha and friends (7) re- ported low sensitivy of preoperative CT. Hyun and In this case, we report high FDG-avidity and dif- friends (2) reported a case in which FDG PET/CT was fuse metastatic disease in this presentation of ACC. a useful tool in dedifferentiated ACC. The pathologi- Hence, we conclude PET/CT could be valuable tool cal features of high grade ACC include tumor necro- evaluating and managing the disease. References 1. Lin WN, Huang HC, Wu CC, Liao CT, Chen IH, Kan 4. Zook JD, Djurasovic M, Dimar JR 2nd, Carreon CJ, et al. Analysis of acinic cell carcinoma of the LY. Spinal metastasis from acinic cell carcino- parotid gland - 15 years experience. Acta Otolar- ma of the parotid gland: a case report. Spine J. yngol 2010;130(12):1406-10. 2012;12(8):e7-10. 2. Hyun O J, Yoo IeR, Jung CK, Hoon Kim S, Chung 5. Laskawi R, Rodel R, Zirk A, Arglebe C,. Retrospec- SK. F-18 FDG PET/CT findings of dedifferen- tive analysis of 35 patients with acinic cell carci- tiated acinic cell carcinoma. Clin Nucl Med. noma of the parotid gland. 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