Fine needle aspiration biopsy: a delicate art

Fine needle aspiration biopsy (FNAB) can provide certain information about intraocular tumors. Interestingly, biopsies are used infrequently in most patients in most centers and the procedure is not considered in diagnostic evaluations of patients with tumors, said Zelia Maria de Silva Corrêa, MD, from the Department of Ophthalmology, University of Cincinnati, Cincinnati, OH, United States.

"There is no list of the true information that can be obtained from FNAB," Dr. Corrêa said. "However, the procedure can tell us about the cohesiveness of the tumor cells, the morphology of the tumor cells, the immunocytochemical features, protein expression, and the procedure provides genetic profiling. FNAB is used as adjunctive to clinical experience."

The reasons she gave for the infrequent use of FNAB are the belief that clinical diagnostic accuracy is high, concern that biopsy can cause high rates of specific complications such as retinal tears or retinal detachment, and concern that biopsy will disseminate tumor cells.

Indications for FNAB include suspected metastatic carcinoma; major diagnosis uncertainty in cases with amelanotic melanoma versus metastasis, metastatic carcinoma versus lymphoma, or leukemic relapse versus microbial infiltration; and request by an informed patient, Dr. Corrêa explained. Controversial indications include choroidal nevus versus melanoma, probable melanoma, and presumed pseudo-retinoblastoma.

"Biopsy can be performed either by transcleral direct penetration of the tumor or through the pars plana," she said. Dr. Corrêa performs biopsies through indirect observation with an indirect lens using a 25-gauge needle. Needle length depends on the location of the tumor; she emphasized the importance of using a caliper to make certain the biopsy is done at the correct location.

"The results of biopsy can be very accurate after sampling three of four sites of the tumor, as we have been doing recently," she stated.