Diagnostic difficulties in orbital pathology

Purpose To describe and discuss sources of difficulty in histopathological diagnosis in orbital pathology and the approach to problematic diagnostic cases. Methods Review of case material in Manchester Royal Eye Hospital and Manchester National Specialist Ophthalmic Pathology Service Laboratory archives and review of the literature. Results Problems may be due to inadequacies of the process of specimen submission/handling, eg inadequate clinical information, inadequate sampling or crush/cautery artefact in small biopsies. They may be due to insufficient or uncertain histopathological criteria, eg isolated or rare orbital presentation of systemic pathology (such as isolated orbital Wegener’s granulomatosis), isolated presentation of metastatic malignancy with unknown primary site, anaplastic malignancy and other lesions of uncertain histogenesis, inflammatory lesion vs lymphoreticular neoplasm (such as lymphoid hyperplasia vs low grade B‐cell non‐Hodgkin’s lymphoma and necrotizing inflammation vs T/NK cell lymphoma). Conclusion Good communication between clinicians and pathologists is essential at all stages during the diagnostic process. Sound morphological assessment remains crucial. Immunohistochemistry plays a valuable part in assisting diagnosis of lesions of uncertain histogenesis and in lymphoreticular pathology. There is an expanding use of molecular genetic analysis. Electron microscopy has largely been supplanted by immunohistochemistry but still has a role to play. Despite the vastly increased technological armamentarium there remain lesions which are very difficult to diagnose or classify. The multidisciplinary team approach fosters interplay among the differing areas of clinical and diagnostic expertise and allows a rational approach to diagnosis and management of problematic cases.