Two articles from the same institution in this issue of the Journal address the issue of biopsy of iris tumors. The authors of these articles describe the biopsy instrumentation and technique they used and provide summary performance data on their biopsy method. The authors of these articles did not mention their clinical diagnosis or differential diagnosis for the tumors in their series, their clinical diagnostic accuracy, the specific indications for biopsy in each case, or the proportion of patients in whom the results of biopsy altered their subsequent patient management.
These articles raise the important question: “What constitutes an ideal biopsy technique for iris tumors?” An answer to this question must address (1) why a biopsy is performed in an individual or group of patients, (2) what type of specimen the biopsy is expected to yield, and (3) what impacts the results of the specimen testing are intended to have for the patient.
Why are Biopsies Performed?
Whenever biopsy of an intraocular tumor is contemplated, both the ophthalmologist recommending the procedure and the patient must understand the intent of the biopsy. Sometimes the intent is clearly to establish or confirm the clinical diagnosis of an intraocular tumor detected on ophthalmic examination or ancillary diagnostic testing. In other cases, the intent of the biopsy may be investigational (eg, to evaluate the performance of a particular biopsy technique or clinical diagnostic accuracy) or prognostic (eg, to obtain a specimen of a uveal tumor diagnosed clinically as a melanoma for prognostic gene expression profiling).
Diagnostic Biopsies
Diagnostic biopsies are performed in vivo before tumor treatment. They can be performed on tumors or lesions of many different types involving different intraocular sites (eg, choroid, retina, ciliary body, iris, vitreous). Three criteria must be fulfilled for a biopsy to be regarded as diagnostic: (1) substantial likelihood that the tumor is a malignant neoplasm or a microbial mass, (2) substantial likelihood that the results of biopsy will influence subsequent patient management significantly, and (3) major diagnostic uncertainty. We recognize that clinical diagnosis is always an exercise in probability and that the correct clinical diagnosis can never be regarded as completely certain; however, we regard only biopsies performed on tumors assigned a differential diagnosis clinically by an experienced ophthalmologist to be truly diagnostic.
Confirmatory Biopsies
Confirmatory biopsies are also performed in vivo before tumor treatment. The principal factor distinguishing confirmatory from diagnostic biopsies is the unequivocal clinical diagnosis assigned to tumors in this category. Confirmatory biopsies are intended either (1) to convince a skeptical patient about the nature of his or her tumor and the need for treatment or (2) to justify a method of treatment for a disorder likely to be multisystem in nature (eg, metastatic carcinoma), for which treatment is likely to be complex or associated with significant potential side effects (eg, intravenous chemotherapy), or both.
Investigational Biopsies
Investigational biopsies may be performed on intraocular tumors of different clinical diagnoses (eg, studies of clinical diagnostic accuracy in which the pathologic diagnosis based on biopsy is regarded as the correct diagnosis, and studies of cytopathologic–histopathologic correlation) or of a single type (eg, studies of prognostic significance of specific chromosomal abnormalities in clinically diagnosed melanocytic uveal tumors). In the case of investigations of a new biopsy technique, the technique should be performed in several freshly enucleated eyes before applying it clinically to make sure that it performs as expected. When an ophthalmologist introduces a new technique into clinical settings, it should be only in the context of an investigational research protocol reviewed and approved by an accredited institutional review board.
Prognostic Biopsies
Prognostic biopsies are performed on intraocular tumors of unequivocal clinical type (currently limited to uveal melanoma) and are intended to yield a specimen of the tumor for noninvestigational classification of the patient’s risk of developing metastasis. In patients with primary uveal melanoma treated by enucleation or transscleral en bloc tumor resection, the biopsy usually is performed immediately after the eye or tumor is removed. In contrast, in patients treated by methods intended to be eye preserving (eg, 125 I plaque radiotherapy, proton beam irradiation), the biopsy usually is performed during or before tumor treatment and by established clinical biopsy methods.
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