Correlation of B-scan, CT scan and biopsy findings in orbital masses (space occupying lesions)

Abstract

Introduction : Orbital masses or space occupying lesions, involving the orbit, produce symptoms and signs by compression, infiltration and/or infarction of orbital structures. A wide variety of processes can produce space-occupying lesions in and around the orbit. Imaging can be done to precisely localize a lesion, to help establish a diagnosis or generate a differential diagnosis that guides management. Material and Methods : Over a period of 18 months, patients with space occupying lesion of the orbit, in the age group of 1 to 70 years are included in the study. Proptosis assessment was done. Results: All the patients were subjected to B scan, CT scan and biopsy. On comparing the findings of B-Scan, CT Scan and biopsy (biopsy findings being taken as gold standard), B-Scan accurately diagnosed 83.33% of the cases, where as CT scan diagnosed only 60% of the cases accurately. Rest of the cases, there was no correlation between the B-Scan/CT scan and biopsy. Conclusions: B-Scan appears to be the better diagnosing tool in identifying most of the orbital lesions when compared to the CT scan. Considering radiation exposure, repeated examination, cost effectiveness and time consumption, B-Scan is advantageous over CT scan in the initial work up and follow up of cases. 2 cases of lymphangioma were identified during the study. In both cases B-Scan showed irregular outline, borders are moderately well defined. Tumor is not encapsulated and extends diffusely through the orbit. Internal structure is irregular due to mix of high and low reflectivity. CT scan showed lesion with irregular margin, multiloculated, heterogenous lesion and enhance prominently with contrast. On histopathology, they appeared as large lymphatic channels in loose connective tissue stroma, focally disorganized smooth muscle in wall of larger channels, peripheral lymphoid aggregates are seen (Figure 4,5). Optic nerve gliomais demonstrated as smooth fusiform or ovoid mass replacing the normal optic nerve void with low- medium reflectivity, whereas on CT, it is seen as nopdular or fusiform enlargement of the optic nerve with contrast enhancement. On histopathology – low grade pilocyticastrocytomas with round to spindled nuclei and dendrite like cytoplasmic processes, with marked pleomorphism, necrosis, vascular proliferation and tumor cells in pools of mucin are seen. One case of lymphoma identified in the present study was accurately diagnosed by B-Scan, which was well circumscribed with smooth contour, diffuse/irregularly shaped, attached to extraocular muscle, but CT scan demonstrated it as a Pseudotumor. Both B-Scan and CT were unable to identify the case of mucormycosis in the present study. B-Scan identified it as infiltrative mass and CT identified it as carcinoma maxillary antrum involving the orbit.