Oncocytic Lipoadenoma of the Parotid Gland: Cytological Findings and Differential Diagnosis on Fine-Needle Aspiration Mohammad Javad Ashraf, M.D.,1 Negar Azarpira, M.D.,1 Mohammad Hossein Anbardar, M.D.,1* and Seyed Basir Hashemi, M.D.2
Oncocytic lipoadenoma is a rare benign neoplastic lesion of salivary gland. To the best of our knowledge, the detailed cytomorphological findings were described only in two cases. We are reporting a 56-year-old woman who presented with 1-year history of right parotid gland mass. Cytologic examination revealed tight clusters of bland looking oncocytic ductal cells with few aggregates of mature adipose tissue in a lipoid background and a benign oncocytic tumor of parotid gland was rendered. Histologically, a tumor with islands of oncocytic epithelial cells admixed with abundant mature adipose tissue was identified. Oncocytic lipoadenoma despite its rarity should be considered in the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes especially those which are accompanied by mature adipose tissue and lipoid background. Diagn. Cytopathol. 2015;43:72–74. VC 2014 Wiley Periodicals, Inc.
Key Words:
oncocyte; lipoadenoma; salivary gland; cytology
Oncocytic lipoadenoma of salivary gland is an extremely uncommon benign tumor which was not included in the 2005 World Health Organization classification of tumors of the salivary glands. To date, few cases of this tumor have been reported in the literature included only two detailed cytomorphologic description. This tumor is well encapsulated and consists of an oncocytic epithelial component admixed with mature adipose tissue.1–6 Here, we report the cytological findings of oncocytic lipoadenoma of parotid gland and discuss its differential diagnosis. 1
Department of Pathology, Shiraz Medical School, Shiraz, Iran Department of Otolaryngology, Shiraz Medical School, Shiraz, Iran *Correspondence to: Mohammad Hossein Anbardar, M.D., Department of Pathology, Shiraz University of Medical Sciences, PO Box: 71345-1864, Shiraz, Iran. E-mail: [email protected] Received 23 November 2013; revised 21 January 2014; Accepted 16 February 2014 DOI: 10.1002/dc.23135 Published online 3 March 2014 in Wiley Online Library (wileyonlinelibrary.com).
Case Report The patient was a 56-year-old woman presenting with a 1-year history of right parotid gland mass. The mass was painless, soft, and slow-growing. Her past medical history was unremarkable. Physical examination revealed a 3 3 3 cm2 nontender, soft, and mobile mass in the superficial lobe of the right parotid gland. However, there was no sign of adhesion to the overlying skin. Fine-needle aspiration was performed using a 22-gauge needle. The smears were stained with Wright-Giemsa and Papanicolaou stain. Cytologic examination revealed tight clusters of oncocytic ductal cells with few aggregates of mature adipose tissue in a lipoid background. Moreover, the oncocytic cells were arranged in microacini and small sheets with no atypical change. Additionally, no cytoplasmic vacuole was seen and no inflammatory cells were present (Figs. 1 and 2). According to these cytologic findings, a benign oncocytic tumor of parotid gland was rendered, but the presence of mature adipose tissue was not matched with this diagnosis. The patient underwent a right superficial lobe parotidectomy. Cut section showed a well-defined, yellow, homogenous mass measuring 3 3 3 3 3 cm3 (Fig. 3). Microscopically, the mass showed islands of oncocytic epithelial cells admixed with abundant mature adipose tissue. There was no ductuloacinar component (Fig. 4). Furthermore, ultrastructural study showed abundant mitochondria in the cytoplasm of oncocytic cells. According to these histological and ultrastructural findings, the diagnosis of oncocytic lipoadenoma was confirmed.
2
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Discussion Oncocytic lipoadenoma is a rare benign neoplastic lesion of salivary gland which was first reported by Hirokawa et al.6 in 1998. Histologically this tumor is composed of mature adipose tissue intermingled with micronodules and islands of oncocytic cells without atypia and mitosis.1–6 C 2014 WILEY PERIODICALS, INC. V
Diagnostic Cytopathology DOI 10.1002/dc
ONCOCYTIC LIPOADENOMA OF THE PAROTID GLAND
Fig. 1. FNA smear shows a fragment of mature adipose tissue and clusters of oncocytic ductal cells with micro acini pattern (Papanicolaou, 3250). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 3. Cut section of parotid mass shows a well defined, yellow, and homogenous mass. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 2. FNA smear shows a fragment of mature adipose tissue and cluster of oncocytic ductal cells in lipoid background (Wright, 3400). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 4. Histolocical section of mass shows islands of oncocytic epithelial cells admixed with abundant mature adipose tissue (Hematoxylin and Eosin, 3100), High power view (inset, 3400). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary. com.]
We described the cytological, histopathological, and ultrastructural findings of a rare case of oncocytic lipoadenoma of parotid gland. To date, about 10 cases of this entity have been documented in the literature. Out of these cases, five underwent fine-needle aspiration before parotidectomy which only Chahwala et al. and Tokyol et al. reported detailed cytological findings.1–5 The cytological findings described by Chahwala et al.1 included moderate cellular smears including oncocytic epithelial cells along with occasional fibrovascular and adipose tissue fragments in prominent lipoid background. However,
only oncocytic cells were detected in three other reports.2,4,5 Cytologic findings in the last report included acinar epithelial cells with a background of inflammatory cells.3 In our case, the smears showed moderate cellularity composed of clusters of bland looking oncocytic epithelial cells and fragments of mature adipose tissue in a lipoid background. According to these cytological findings, we considered a benign oncocytic tumor of parotid gland such as oncocytoma. Oncocytes, distinctive epithelial cells by abundant eosinophilic granular cytoplasm, may be seen in aspirates from varying conditions ranging from normal glands of Diagnostic Cytopathology, Vol. 43, No 1
73
Diagnostic Cytopathology DOI 10.1002/dc
ASHRAF ET AL.
elderly individuals to neoplastic lesions such as oncocytoma (benign and malignant), Warthin’s tumor, pleomorphic adenoma, mucoepidermoid carcinoma, and rarely acinic cell carcinoma.7,8 Therefore, precise diagnosis by fine-needle aspiration cytology is very difficult. Oncocytic cells in salivary glands can be classified as oncocytic metaplasia, oncocytosis, and oncocytoma (benign and malignant). Areas of oncocytic metaplasia can be seen in a variety of tumors, such as basal cell adenoma, pleomorphic adenoma, and myoepithelioma.7,8 Thus, the fineneedle aspiration of these entities shows combination of cytological findings of that tumor accompanied by oncocytic cells. The cytological findings in oncocytosis and benign oncocytoma show sheets of oncocytic cells; however, their differentiation on cytology is difficult. As the oncocytoma can appear cytologically malignant looking, differentiation from oncocytic carcinoma is also difficult.8 In our case, the best matching diagnosis was benign oncocytoma at first. However, the presence of fragments of mature adipose tissue and lipoid background could be a guide to diagnosis of oncocytic lipoadenoma. The three main components in the fine-needle aspiration cytology of Warthin’s tumor are oncocytes, lymphocytes, and dirty background.7,9,10 Hence, we excluded Warthin’s tumor due to lack of lymphoid component and dirty background. Moreover, pleomorphic adenoma with oncocytic metaplasia cytologically shows extracellular matrix, myoepithelial and ductal cells, and oncocytes.10 The patient under the present study lacked matrix and myoepithelial cells. Fine-needle aspiration of mucoepidermoid carcinoma can rarely show oncocyte-like cells. Nevertheless, presence of mucus secreting and intermediate cells can be helpful in differential diagnosis with oncocytic lipoadenoma.10 Cytologically the tumor cells of acinic cell carcinoma may appear oncocytic. In acinic cell carcinoma, however, the cells are more granular and finely vacuolated, the nuclei appear larger with more pleomorphism, and usually there are naked nuclei.8,10 In the current study, we reported a case of oncocytic lipoadenoma of parotid gland with emphasis on cytologi-
74
Diagnostic Cytopathology, Vol. 43, No 1
cal findings and discussed the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes. Despite its rarity, oncocytic lipoadenoma should be considered in the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes, especially those that are accompanied by mature adipose tissue and lipoid background.
Acknowledgment The authors thank Ms. A. Keivanshekouh at the Research Improvement Center of Shiraz University of Medical Sciences for improving the use of English in the manuscript.
References 1. Chahwala Q, Siddaraju N, Singh N, Goneppanavar M, Basu D. Fine needle aspiration cytology of oncocytic lipoadenoma of the parotid gland: Report of a rare case. Acta Cytol 2009;53:437–439. 2. Aouad R, Matar N, Sader-Ghorra C, Haddad A. Pathology quiz case 1. Oncocytic lipoadenoma of the parotid gland. Arch Otolaryngol Head Neck Surg 2008;134:446–448. 3. McNeil ML, Bullock MJ, Trites JR, Hart RD, Taylor SM. Oncocytic lipoadenoma of the parotid gland with sebaceous differentiation in a 73-year-old male. J Otolaryngol Head Neck Surg 2010;39: E48–E50. 4. Tokyol C, Dilek FH, Aktepe F, Ayc¸ic¸ek A, Altuntas¸ A. Oncocytic lipoadenoma of the parotid gland: A case report with fine needle aspiration cytology findings. Kulak Burun Bogaz Ihtis Derg 2010; 20:146–149. 5. Devadoss CW, Murugan P, Basu D, Jagdish S. Oncocytic lipoadenoma of the parotid gland: Report of a rare case. J Clin Diagn Res 2012;6:1076–1078. 6. Hirokawa M, Shimizu M, Manabe T, Ito J, Ogawa S. Oncocytic lipoadenoma of the submandibular gland. Hum Pathol 1998;29: 410–412. 7. Verma K, Kapila K. Salivary gland tumors with a prominent oncocytic component. Cytologic findings and differential diagnosis of oncocytomas and Warthin’s tumor on fine needle aspirates. Acta Cytol 2003;47:221–226. 8. Chakrabarti I, Basu A, Ghosh N. Oncocytic lesion of parotid gland: A dilemma for cytopathologists. J Cytol 2012;29:80–82. 9. David O, Blaney S, Hearp M. Parotid gland fine-needle aspiration cytology: An approach to differential diagnosis. Diagn Cytopathol 2007;35:47–56. 10. Mukunyadzi P. Review of fine-needle aspiration cytology of salivary gland neoplasms, with emphasis on differential diagnosis. Am J Clin Pathol 2002;118(Suppl):S100–S15.
Oncocytic lipoadenoma is a rare benign neoplastic lesion of salivary gland. To the best of our knowledge, the detailed cytomorphological findings were described only in two cases. We are reporting a 56-year-old woman who presented with 1-year history of right parotid gland mass. Cytologic examination revealed tight clusters of bland looking oncocytic ductal cells with few aggregates of mature adipose tissue in a lipoid background and a benign oncocytic tumor of parotid gland was rendered. Histologically, a tumor with islands of oncocytic epithelial cells admixed with abundant mature adipose tissue was identified. Oncocytic lipoadenoma despite its rarity should be considered in the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes especially those which are accompanied by mature adipose tissue and lipoid background. Diagn. Cytopathol. 2015;43:72–74. VC 2014 Wiley Periodicals, Inc.
Key Words:
oncocyte; lipoadenoma; salivary gland; cytology
Oncocytic lipoadenoma of salivary gland is an extremely uncommon benign tumor which was not included in the 2005 World Health Organization classification of tumors of the salivary glands. To date, few cases of this tumor have been reported in the literature included only two detailed cytomorphologic description. This tumor is well encapsulated and consists of an oncocytic epithelial component admixed with mature adipose tissue.1–6 Here, we report the cytological findings of oncocytic lipoadenoma of parotid gland and discuss its differential diagnosis. 1
Department of Pathology, Shiraz Medical School, Shiraz, Iran Department of Otolaryngology, Shiraz Medical School, Shiraz, Iran *Correspondence to: Mohammad Hossein Anbardar, M.D., Department of Pathology, Shiraz University of Medical Sciences, PO Box: 71345-1864, Shiraz, Iran. E-mail: [email protected] Received 23 November 2013; revised 21 January 2014; Accepted 16 February 2014 DOI: 10.1002/dc.23135 Published online 3 March 2014 in Wiley Online Library (wileyonlinelibrary.com).
Case Report The patient was a 56-year-old woman presenting with a 1-year history of right parotid gland mass. The mass was painless, soft, and slow-growing. Her past medical history was unremarkable. Physical examination revealed a 3 3 3 cm2 nontender, soft, and mobile mass in the superficial lobe of the right parotid gland. However, there was no sign of adhesion to the overlying skin. Fine-needle aspiration was performed using a 22-gauge needle. The smears were stained with Wright-Giemsa and Papanicolaou stain. Cytologic examination revealed tight clusters of oncocytic ductal cells with few aggregates of mature adipose tissue in a lipoid background. Moreover, the oncocytic cells were arranged in microacini and small sheets with no atypical change. Additionally, no cytoplasmic vacuole was seen and no inflammatory cells were present (Figs. 1 and 2). According to these cytologic findings, a benign oncocytic tumor of parotid gland was rendered, but the presence of mature adipose tissue was not matched with this diagnosis. The patient underwent a right superficial lobe parotidectomy. Cut section showed a well-defined, yellow, homogenous mass measuring 3 3 3 3 3 cm3 (Fig. 3). Microscopically, the mass showed islands of oncocytic epithelial cells admixed with abundant mature adipose tissue. There was no ductuloacinar component (Fig. 4). Furthermore, ultrastructural study showed abundant mitochondria in the cytoplasm of oncocytic cells. According to these histological and ultrastructural findings, the diagnosis of oncocytic lipoadenoma was confirmed.
2
72
Diagnostic Cytopathology, Vol. 43, No 1
Discussion Oncocytic lipoadenoma is a rare benign neoplastic lesion of salivary gland which was first reported by Hirokawa et al.6 in 1998. Histologically this tumor is composed of mature adipose tissue intermingled with micronodules and islands of oncocytic cells without atypia and mitosis.1–6 C 2014 WILEY PERIODICALS, INC. V
Diagnostic Cytopathology DOI 10.1002/dc
ONCOCYTIC LIPOADENOMA OF THE PAROTID GLAND
Fig. 1. FNA smear shows a fragment of mature adipose tissue and clusters of oncocytic ductal cells with micro acini pattern (Papanicolaou, 3250). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 3. Cut section of parotid mass shows a well defined, yellow, and homogenous mass. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 2. FNA smear shows a fragment of mature adipose tissue and cluster of oncocytic ductal cells in lipoid background (Wright, 3400). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 4. Histolocical section of mass shows islands of oncocytic epithelial cells admixed with abundant mature adipose tissue (Hematoxylin and Eosin, 3100), High power view (inset, 3400). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary. com.]
We described the cytological, histopathological, and ultrastructural findings of a rare case of oncocytic lipoadenoma of parotid gland. To date, about 10 cases of this entity have been documented in the literature. Out of these cases, five underwent fine-needle aspiration before parotidectomy which only Chahwala et al. and Tokyol et al. reported detailed cytological findings.1–5 The cytological findings described by Chahwala et al.1 included moderate cellular smears including oncocytic epithelial cells along with occasional fibrovascular and adipose tissue fragments in prominent lipoid background. However,
only oncocytic cells were detected in three other reports.2,4,5 Cytologic findings in the last report included acinar epithelial cells with a background of inflammatory cells.3 In our case, the smears showed moderate cellularity composed of clusters of bland looking oncocytic epithelial cells and fragments of mature adipose tissue in a lipoid background. According to these cytological findings, we considered a benign oncocytic tumor of parotid gland such as oncocytoma. Oncocytes, distinctive epithelial cells by abundant eosinophilic granular cytoplasm, may be seen in aspirates from varying conditions ranging from normal glands of Diagnostic Cytopathology, Vol. 43, No 1
73
Diagnostic Cytopathology DOI 10.1002/dc
ASHRAF ET AL.
elderly individuals to neoplastic lesions such as oncocytoma (benign and malignant), Warthin’s tumor, pleomorphic adenoma, mucoepidermoid carcinoma, and rarely acinic cell carcinoma.7,8 Therefore, precise diagnosis by fine-needle aspiration cytology is very difficult. Oncocytic cells in salivary glands can be classified as oncocytic metaplasia, oncocytosis, and oncocytoma (benign and malignant). Areas of oncocytic metaplasia can be seen in a variety of tumors, such as basal cell adenoma, pleomorphic adenoma, and myoepithelioma.7,8 Thus, the fineneedle aspiration of these entities shows combination of cytological findings of that tumor accompanied by oncocytic cells. The cytological findings in oncocytosis and benign oncocytoma show sheets of oncocytic cells; however, their differentiation on cytology is difficult. As the oncocytoma can appear cytologically malignant looking, differentiation from oncocytic carcinoma is also difficult.8 In our case, the best matching diagnosis was benign oncocytoma at first. However, the presence of fragments of mature adipose tissue and lipoid background could be a guide to diagnosis of oncocytic lipoadenoma. The three main components in the fine-needle aspiration cytology of Warthin’s tumor are oncocytes, lymphocytes, and dirty background.7,9,10 Hence, we excluded Warthin’s tumor due to lack of lymphoid component and dirty background. Moreover, pleomorphic adenoma with oncocytic metaplasia cytologically shows extracellular matrix, myoepithelial and ductal cells, and oncocytes.10 The patient under the present study lacked matrix and myoepithelial cells. Fine-needle aspiration of mucoepidermoid carcinoma can rarely show oncocyte-like cells. Nevertheless, presence of mucus secreting and intermediate cells can be helpful in differential diagnosis with oncocytic lipoadenoma.10 Cytologically the tumor cells of acinic cell carcinoma may appear oncocytic. In acinic cell carcinoma, however, the cells are more granular and finely vacuolated, the nuclei appear larger with more pleomorphism, and usually there are naked nuclei.8,10 In the current study, we reported a case of oncocytic lipoadenoma of parotid gland with emphasis on cytologi-
74
Diagnostic Cytopathology, Vol. 43, No 1
cal findings and discussed the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes. Despite its rarity, oncocytic lipoadenoma should be considered in the differential diagnosis of salivary gland fine-needle aspirations containing oncocytes, especially those that are accompanied by mature adipose tissue and lipoid background.
Acknowledgment The authors thank Ms. A. Keivanshekouh at the Research Improvement Center of Shiraz University of Medical Sciences for improving the use of English in the manuscript.
References 1. Chahwala Q, Siddaraju N, Singh N, Goneppanavar M, Basu D. Fine needle aspiration cytology of oncocytic lipoadenoma of the parotid gland: Report of a rare case. Acta Cytol 2009;53:437–439. 2. Aouad R, Matar N, Sader-Ghorra C, Haddad A. Pathology quiz case 1. Oncocytic lipoadenoma of the parotid gland. Arch Otolaryngol Head Neck Surg 2008;134:446–448. 3. McNeil ML, Bullock MJ, Trites JR, Hart RD, Taylor SM. Oncocytic lipoadenoma of the parotid gland with sebaceous differentiation in a 73-year-old male. J Otolaryngol Head Neck Surg 2010;39: E48–E50. 4. Tokyol C, Dilek FH, Aktepe F, Ayc¸ic¸ek A, Altuntas¸ A. Oncocytic lipoadenoma of the parotid gland: A case report with fine needle aspiration cytology findings. Kulak Burun Bogaz Ihtis Derg 2010; 20:146–149. 5. Devadoss CW, Murugan P, Basu D, Jagdish S. Oncocytic lipoadenoma of the parotid gland: Report of a rare case. J Clin Diagn Res 2012;6:1076–1078. 6. Hirokawa M, Shimizu M, Manabe T, Ito J, Ogawa S. Oncocytic lipoadenoma of the submandibular gland. Hum Pathol 1998;29: 410–412. 7. Verma K, Kapila K. Salivary gland tumors with a prominent oncocytic component. Cytologic findings and differential diagnosis of oncocytomas and Warthin’s tumor on fine needle aspirates. Acta Cytol 2003;47:221–226. 8. Chakrabarti I, Basu A, Ghosh N. Oncocytic lesion of parotid gland: A dilemma for cytopathologists. J Cytol 2012;29:80–82. 9. David O, Blaney S, Hearp M. Parotid gland fine-needle aspiration cytology: An approach to differential diagnosis. Diagn Cytopathol 2007;35:47–56. 10. Mukunyadzi P. Review of fine-needle aspiration cytology of salivary gland neoplasms, with emphasis on differential diagnosis. Am J Clin Pathol 2002;118(Suppl):S100–S15.
