AIM: To analyze the clinical and histopathological composition of orbital tumors and tumor-like lesions.

METHODS: Retrospective case-series study. The clinical histopathological data of 699 cases(707 eyes)with orbital tumor and tumor-like lesions who treated in the orbital disease and ophthalmic plastic department of Tianjin Eye Hospital between January 2010 and December 2020 were collected. All the pathology diagnosis results were divided into three categories which were benign tumor, borderline tumor and malignant tumor according to the eighth edition of the American Joint Committee on Cancer staging system and the 2018 World Health Organization Classification of tumors of the eye. All cases were divided into four groups according to age, including 0～17 years old, 18～39 years old, 40～59 years old, 60 years and above. The histological composition of each group was analyzed.

RESULTS: Among the 699 cases(707 eyes), 311 patients(316 eyes)were male and 388 patients(391 eyes)were female. The patient's age at diagnosis ranged from 1 to 84 years(mean 39.9±2.2)years. The right orbit was involved in 307 patients, the left orbit in 384 patients, and 8 patients in bilateral orbit. There were 598 patients(604 eyes, 85.6%)with benign tumor and tumor-like lesions, 7 patients(7 eyes, 1.0%)with borderline tumor, and 94 patients(96 eyes, 13.4%)with malignant tumors. The top 5 benign tumor and tumor-like lesions were cavernous hemangioma(110 cases, 15.7%), dermoid cysts(96 cases, 13.7%), pleomorphic adenomas(54 cases, 7.7%), inflammatory pseudotumors(38 cases, 5.4%), and schwannomas(29 cases, 4.1%)respectively. The top 5 borderline and malignant tumors were non-Hodgkin lymphomas(42 cases, 41.6%), solitary fibrous tumors(12 cases, 11.9%), adenoid cystic carcinomas(11 cases, 10.9%), metastatic tumor(9 cases, 8.9%), and rhabdomyosarcoma(8 cases, 7.9%), respectively. Among the common orbital benign tumors and tumor-like lesions, cavernous hemangioma and pleomorphic adenoma showed a female predominance. Among the common borderline and malignant tumors, non-Hodgkin lymphoma and mesenchymal chondrosarcoma showed a male predominance. The most common benign and malignant tumors were dermoid cysts, rhabdomyosarcomas respectively in group under 18 years old. And dermoid cysts and solitary fibrous tumors were the most common benign and malignant tumors respectively in patients between 18 and 39 years old. Cavernous hemangioma and non-Hodgkin lymphomas were the most common benign and malignant tumors respectively in patients between 40 and 59 years old. While cavernous hemangioma and non-Hodgkin lymphomas were the most common benign and malignant tumors respectively in cases over 60 years old.

CONCLUSION: Most orbital tumors and tumor-like lesions are benign. The most common benign orbital tumor is cavernous hemangioma, followed by dermoid cyst. Non-Hodgkin lymphoma is the most common malignant orbital tumor.