The 5th Edition of the World Health Organization Classification of Tumours of the Eye and Orbit

Abstract

The 5th edition of the World Health Organization (WHO) Classification of Tumours of the Eye and Orbit is the latest step in standardizing the diagnostic practice worldwide. Building upon the 4th edition, published in 2018, the 5th edition introduces new chapters on the eyelid and orbital tumors, and consolidates sections on hematolymphoid tumors, soft tissue and bone tumors, metastases and genetic tumor predisposition syndromes into dedicated chapters. Written in the format of the other 5th edition volumes, a systematic approach is taken to describe the defining characteristics of each tumor type and its staging, with the addition of macroscopic appearance, cytology, diagnostic molecular pathology, and essential and desirable diagnostic criteria. This volume highlights recent advances in the etiology, pathogenesis, and diagnosis of tumors of the eye and ocular adnexa. Radiologic and ophthalmic features are also emphasized. Moreover, the 5th edition includes updates on the classification scheme for certain tumors, such as vascular anomalies, and introduces tumors that have been recently identified in the eye and ocular adnexa. This editorial summarizes the major general changes in the 5th edition of the WHO classification of Tumours of the Eye and Orbit, and the specific updates in each taxonomic category, with an emphasis on advances in understanding tumor pathogenesis, diagnostic and prognostic criteria, and novel immunohistochemical and molecular markers.

Epibulbar Complex Choristoma Containing Bone: A Case Report and Closer Look at Classifications

“…The subsequent finding of centrally located bone conflicted with this diagnosis. According to the 5th edition of the WHO Classification of eye and orbital tumours, an epibulbar complex choristoma may contain additional “heterotrophic tissues like bone, cartilage, nerve, and skeletal muscle” [ 3 ]. This lesion would thus be regarded as an epibulbar complex choristoma containing bone.…”

“…Choristomas can be found within the bulbar conjunctiva and may contain various tissue types. Based on the tissue types contained within, epibulbar choristomas are classified as either epibulbar dermoid, dermolipoma, or complex choristoma [ 3 ]. Unlike other reported cases of epibulbar complex choristoma, this case appeared as an otherwise normal epibulbar dermolipoma both clinically and during surgery.…”

Eyelid Tumors at Razi and Farabi Hospitals, Tehran, Iran

“…This chapter also mentions rare adnexal tumors with a predilection for the eyelid, e.g., sebaceous neoplasms and endocrine mucin-producing sweat gland carcinoma, as well as unique lesions of the eyelid, e.g., phakomatous choristoma and intratarsal keratinous cysts. This material is aligned with the 5th edition of the WHO classification of tumors of the skin, specifically concerning cutaneous melanocytic tumors (4). Specialists performed all the procedures, and a pathologist reported the histopathological types of the tumors.…”

Role of vitreous cytology in the diagnosis of primary central nervous system lymphoma: A report of an unusual presentation

“…Primary IOL (PIOL) arises from different ocular tissues, namely, retina, vitreous, uvea, or Bruch's membrane, among which vitreoretinal are the commonest. 1 According to the recent world health organization, terminology classification of tumors of the Eye and Orbit, primary vitreoretinal large cell B-cell lymphoma (PVRLCBL) is the most common ocular high-grade NHL and is commonly associated with central nervous system involvement. The tumor cells in PVRLBCL are similar to those seen in large B-cell lymphomas of immune-privileged sites (IP-LBCL).…”

“…The tumor cells in PVRLBCL are similar to those seen in large B-cell lymphomas of immune-privileged sites (IP-LBCL). 1 Metastatic involvement of the eye in systemic lymphoma is called secondary IOL. In concurrent IOL, there is simultaneous involvement of the ocular tissues by a PCNSL.…”