Core Biopsy

Lidocaine 1% with epinephrine (1:100,000) should be injected subcutaneously and into the orbit in the region of the tumor approximately 15 to 20 minutes before a fine-needle aspiration or core biopsy. This amount of time offers not only good local anesthesia but also sufficient hemostasis within the orbit. Compression onto the globe and the biopsy site should be applied by hand for approximately 2 minutes after the procedure to ensure hemostasis.

Core biopsy can be performed with different types of instrument consisting of a trephine needle and an obturator (stylet) that fits inside the trephine needle. It is important to use a sharp needle with a stylet properly fixed by a locking device that does not move the needle. The needle harboring the stylet is then introduced into the orbit. When the approximate area of the tumor is reached, the needle is pushed into the tumor with a slight rotary motion. It is difficult to feel soft and partially necrotic tumors, but when firm tumors are penetrated, the surgeon feels a distinct yielding sensation. After the penetration, the stylet is removed and the needle is advanced approximately 0.5

to 1.0 cm, depending on the size of the tumor. The needle is rotated a few times clockwise and then a few times counterclockwise. The thumb is then placed on the hub of the needle, which is extracted with slight lateral movements. With gentle boring and suction application, a considerable amount of tissue can be collected within the chamber of the needle. If the attempt at the biopsy is not successful, the procedure should be repeated from the same entry site. If the second biopsy attempt is also unsuccessful, ultrasound or CT monitoring should be used on the third try.

In some instruments, a spiral fixator that fits into the needle is used instead of negative pressure to bore

FIGURE 12.3. A pediatric corneal trephine (A) can be attached to a straight hemostat to create a useful tool (B) for sampling tumors located in the anterior and mid orbit.

FIGURE 12.2. Core biopsy being performed with Jamshidi needle following local anesthesia. The Jamshidi needle's shaft distends slightly toward the tip to allow a generous tumor sample to be pulled into the needle.

FIGURE 12.3. A pediatric corneal trephine (A) can be attached to a straight hemostat to create a useful tool (B) for sampling tumors located in the anterior and mid orbit.

into the tumor and pull tissue into the needle shaft. The author prefers to perform core biopsies with a Jamshidi bone marrow biopsy needle (Figure 12.2); because of the slight distention at the end of the needle, more tissue can be pulled into the shaft of the instrument.

If the lesion is anteriorly located and covered with a conjunctival surface, core biopsies can be performed with a disposable cutaneous punch or a small-diameter corneal trephine that easily bores into the lesion through the conjunctiva (Figure 12.3). The advantage of the core biopsy over the incisional biopsy is that the former can be done under local anesthesia without elaborate surgical exposure. However in some instances (e.g., fibrotic or nectotic tumors), tissue may not be representative for histopathologic examination, and core biopsy may cause bleeding more readily than FNAB, particularly after several passes. Most of the core biopsy instruments can be utilized under ultrasound or CT guidance (Figure 12.4).2,3

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