RESUMEN CORTO - SHORT SUMMARY
INTRODUCTION The prevalence of cyst-like lymph nodes is low in veterinary medicine. While in human medicine, these are mainly seen in head and neck cancers, in dogs, these can be found in non-cancerous and cancerous conditions, including different types of mesenchymal and epithelial neoplasia. This is the first case report describing a cystic metastatic lymph node in a dog with a subcutaneous mast cell tumour.
MATHERIAL AND METHODS A 9 year-old male neutered Lhasa Apso was referred to the Hospital for Small Animal, University of Edinburgh for staging after cytological diagnosis of a poorly differentiated subcutaneous mast cell tumour (MCT) in area of the right flank.
RESULTS An abdominal ultrasound revealed cranial to the aortic trifurcation, a severely enlarged rounded well-defined (4 cm in diameter), hypoechoic lesion in the region of the right medial iliac lymph node associated with marked perinodal steatitis. A CT scan performed for radiotherapy planning confirmed a large well-defined, rounded, non-enhancing hypoattenuating cystic mass in the area of right medial iliac lymph node, (HU=18).
Fine-needle aspirates taken from the mass yielded, numerous poorly granulated mast cells with moderate anisocytosis and anisokaryosis, and few binucleated cells. A heterogeneous population of lymphocytes and few eosinophils and haemosiderin laden macrophages were also present, consistent with a diagnosis of lymph node with MCT metastasis.
CONCLUSION Cystic-like lymph nodes in dogs diagnosed with mast cell tumours may indicate metastatic infiltration and this should be included in the differential diagnosis when present.
BIBLIOGRAFÍA
- Hoelzler MG, Bellah JR, Donofro MC: Omentalization of cystic sublumbar lymph node metastases for long-term palliation of tenesmus and dysuria in a dog with anal sac adenocarcinoma. J Am Vet Med Assoc 2001;219(12):1729-1708.
- Liotta A, Billen F, Heimann M, et al: Prevalence, location and concurrent diseases of ultrasonographic cyst-like lesions of abdominal lymph nodes in dogs. Vet Rec 2017;180(13):326.
- Gourin CG, Johnson JT: Incidence of unsuspected metastases in lateral cervical cysts. Laryngoscope. 2000;110(10 Pt 1):1637-1641.
- Nuttall FQ: Cystic metastases from papillary adenocarcinoma of the thyroid with comments concerning carcinoma associated with thyroglossal remnants. Am J Surg 1965;109:500-505.
- Mokhtari S: Mechanisms of cyst formation in metastatic lymph nodes of head and neck squamous cell carcinoma. Diagn Pathol 2012;7:6.
- Crist HS, Evans JJ, Mani H, et al: Do black (dark) lymph-node metastases in papillary thyroid carcinoma suggest more advanced or aggressive disease? Thyroid 2013; 23:977–981.
- Llabrés-Díaz FJ: Ultrasonography of the medial iliac lymph nodes in the dog. Vet Radiol Ultrasound 2004; 45(2):156-165.
- Veterinary cooperative oncology group - common terminology criteria for adverse events (VCOG-CTCAE) following chemotherapy or biological antineoplastic therapy in dogs and cats v1.1. Vet Comp Oncol 2016;14(4):417-446.
- Nguyen SM, Thamm DH, Vail DM, London CA: Response evaluation criteria for solid tumours in dogs (v1.0): a Veterinary Cooperative Oncology Group (VCOG) consensus document. Vet Comp Oncol 2015;13(3):176-183.
- De Swarte M, Alexander K, Rannou B et al: Comparison of sonographic features of benign and neoplastic deep lymph nodes in dogs. Vet Radiol Ultrasound 2011; 52(4): 451-456.
- Sato AF, Solano M: Ultrasonographic findings in abdominal mast cell disease: a retrospective study of 19 patients. Vet Radiol Ultrasound 2004;45(1):51-57.
- Ustün M, Risberg B, Davidson B, Berner A: Cystic change in metastatic lymph nodes: a common diagnostic pitfall in fine-needle aspiration cytology. Diagn Cytopathol 2002; 27(6):387-392.
- Kim JK, Kim MJ, Choi SH, et al: Cystic Lateral Lymph Node Metastases From Papillary Thyroid Cancer Patients. Laryngoscope 2020;10.1002/lary.28631.