BACKGROUND
Biopsy, a Greek-derived word (bio-life; opsia-to see) loosely translated as "view of the living," is defined as removal of tissue from the living organisms for the purpose of microscopic examination and diagnosis. A biopsy’s goals are to generate a tissue sample for accurate pathological analysis and begin the therapeutic treatment of the tumor that is causing pain or a disruption in cosmesis or function.1
Proper diagnosis and treatment of a soft tissue hand mass is an integral aspect of any hand surgery practice. Although the overwhelming majority of hand masses encountered are benign, identifying the estimated 3% to 6% of malignancies is of utmost importance6 The essential steps in evaluating a mass involve a comprehensive clinical evaluation including a detailed history, thorough physical examination, and proper imaging. This evaluation combined with an understanding of most likely and most serious diagnoses should guide subsequent treatment decision making. As part of the diagnostic workup, the decision to utilize the biopsy as a diagnostic and therapeutic treatment is a critical step. When a biopsy is indicated, proper technique in retrieving, handling, and sending a specimen is essential to obtaining accurate results that can guide care of the patient. Hand soft tissue tumors are unique with respect to other extremity and axial located tumors because biopsies here simultaneously represent the last stage of the diagnostic workup and first stage of treatment.2
Skin cancers represent the most common primary malignancies of the hand. They typically present as painless lesions on areas of high sun exposure, such as the dorsum of the hand and upper extremity. The most common malignancy is squamous cell carcinoma, followed by basal cell carcinoma and melanoma. The initial step in diagnostic evaluation of a potential skin cancer of the upper extremity should be a biopsy.3
Sentinel lymph node biopsy was introduced as an alternative to routine lymphadenectomy in treating and staging patients with early-stage melanoma.4 It has become an invaluable tool in the management of hand and wrist melanoma and has been similarly used to guide axillary lymph node management in other hand and wrist tumors that travel via lymphatic spread. Its role should not be forgotten in the primary excision of tumors, because disruption of lymphatic pathways via closure and complex reconstruction can alter drainage pathways and potentially affect its accuracy. It has become a standard in oncologic care, and its application should be considered by hand surgeons performing upper extremity tumor excision and reconstruction.5
HISTORICAL OVERVIEW
Ernest Besnier was born in Honfleur, France, on April 21, 1831. He studied medicine in the French capital, Paris, and went on to lead a career in internal medicine and became a consistent contributor to the progress of dermatology. He did much to popularize the study of skin lesions by means of histologic examination of tissue removed during life, a procedure for which he is credited with creating the term biopsy in 1879, now in general use.7 The first diagnostic biopsy in Russia was performed in 1875 by M. M. Rudnev. One of the earliest diagnostic biopsies was developed by the Arab physician Abulcasim (1103-1107AD). A needle was used to puncture a goiter and material was characterized.8 It is possible to make out three stages in more than 100 year history of the method development: an occasional use of histologic procedure involving living organs and tissues accessible for observation and study (approximately until the late 19th century); restricted application of biopsy (until the mid-20th century); present stage at which the method is widely adopted. Currently, the biopsy is in general use with respect to human organism not only in oncology but practically in all clinical specialties.9
DESCRIPTION
OPEN BIOPSY TECHNIQUES
In hand surgery, open/incisional/intralesional biopsy is reserved for indeterminate soft tissue lesions with high probability of malignancy, which is rare. Incisional biopsy is a sampling of the tissue from the tumor itself under direct visualization. This is performed through the tumor bed and used to determine the diagnosis before proceeding with wide margin treatment of a suspected sarcomatous lesion. It may be indicated after a failed or nondiagnostic closed biopsy.10 Incisional biopsy is the most accurate and reliable form of biopsy and has long been considered the gold standard for soft tissue tumors, yielding a diagnostic accuracy of 94% to 100%.2
Open biopsy of extremity masses is still the gold standard of obtaining an accurate pathologic diagnosis, but it is critical that the surgeon follow the established biopsy principles of orthopedic oncology. Most of the principles of biopsy can be understood by realizing (1) musculoskeletal tumors are generally contained within a given volume by a capsule or pseudocapsule, (2) that any biopsy must deliberately puncture this capsule/pseudocapsule and therefore involves seeding of the entire biopsy tract, and (3) even a relatively small amount of residual cancer left behind after definitive tumor resection can result in local recurrence of the tumor. Longitudinal incisions are the workhorse of often complex exposures used for definitive tumor resections in orthopedic oncology. For this reason, an open biopsy should be performed via a longitudinal incision that can be easily incorporated into, or “ellipsed” out of, the definitive resection incision. The surgeon performing open biopsy should go straight down to the tumor without creating soft tissue flaps and without developing intermuscular/internervous planes. Ideally, no critical anatomic structure such as important neurovascular structures shoud be dissected or even visualized during an open biopsy. Because the biopsy will disrupt the tumor capsule, essentially any structure that is visualized during the biopsy will be assumed contaminated with tumor and would therefore have to be removed at the time of definitive resection should the tumor be found to be malignant. Other important principles are that there must be meticulous hemostasis; if the patient is found to have a large hematoma tracking up their extremity after surgery, the entire area of bruising must be assumed contaminated with tumor cells. Meticulous hemostasis, even if it requires prolonged pressure on the area, is always preferable to drains to address postoperative bleeding concerns; if drains must be used, they should be placed in line and just outside the longitudinal biopsy incision. Finally, to reduce the risk of further disrupting tumor capsule, the extremity should be held in elevation for exsanguination and Esmarch exsanguination is contraindicated.2
Excisional or marginal biopsy is reserved for soft tissue lesions with determinate status, lesions less than 2 cm, those located distal to the metacarpophalangeal joints, or those with low risk of malignancy.3 This technique employs an incision directly over the mass and dissection is performed until the mass can be seen. The tumor is shelled out from its surrounding soft tissue attachments. The reactive zone is typically violated and tumor cells may remain in the surgical bed despite removal of the pseudocapsule. This technique is rarely used for indeterminate lesions owing to inadequate resection of an unexpected malignant lesion with positive margins13
Wide margin resection includes tumor excision with negative margins and a cuff of normal tissue around the reactive zone and pseudocapsule. Typically, a 1- to 3-cm periphery of normal tissue is removed but is dictated by relationship of the tumor to nearby structures.5 Excisional biopsy and open incisional biopsy can have several complications relating to sampling of surgical tissue, which include infection, wound dehiscence, hematoma, tumor spread, and contamination of an uninvolved compartment, neurovascular injury, inadequate tissue collection, inadequate margins.11
Unlike open biopsies for deep soft tissue and bone lesions, biopsies for skin cancer can be performed under local anesthesia in the office setting. Often, shave biopsies are sufficient; however, a punch biopsy should be considered for indurated, atrophic, and/or pigmented lesions. A shave biopsy can be performed by infiltrating the lesion locally with lidocaine, with or without epinephrine. A sample can be obtained by either using a half blade for shave biopsy or by simply using a 15 blade in a tangential fashion. Hemostasis can be obtained with aluminum chloride 20% solution, Monsel solution, or through electrocautery. A punch biopsy can be performed by infiltration with local anesthesia as well. The size of the punch biopsy is generally determined by the size of the lesion to be sampled. Punch devices range in size from 1.5 to 8.0 mm. An adequate sample can be obtained in most cases with a 4-mm punch sampling of the lesion. The sample should be directed toward either the most indurated or most pigmented portion of the lesion. Hemostasis of punch biopsies of less than 4 mm in size can usually be achieved by Monsel’s solution, cautery, or closure with a simple suture. Punch biopsies greater than 4 mm in size can often require hemostasis by a simple suture12
CLOSED BIOPSY TECHNIQUES
FINE NEEDLE
The standard technique for fine needle aspiration(FNA) involves a 21- or 22-gauge, 1.0- or 1.5-inch-long needle. After the skin has been cleaned, the mass is examined, and if it can be felt, it is subsequently positioned for needle entry. If the mass cannot be felt, imaging such as ultrasound may be needed to find the exact location and guide the needle. At least 3 aspirations are typically carried out in each case, and several passes may be made during each aspiration. After aspiration, the needle is rinsed into cell culture media after making conventional smears. An initial assessment is then performed by staining some of the air-dried smears with a Romanowsky stain, and the remaining slides with a modified Papanicolaou stain after rehydration. From a clinical point of view, lesions are classified as either superficial or deep-seated. Cytologically, aspirates are typically classified into 1 of 5 categories:
- Benign aspirate without a specific cytohistologic diagnosis
- Benign aspirate with a specific cytohistologic diagnosis
- Atypical aspirate
- Malignant aspirate without a specific cytohistologic diagnosis
- Malignant aspirate with a specific cytohistologic diagnosis.14, 15, 16
FNA has the advantages of speed, convenience, decreased cost, minimal morbidity, and a theoretically lower risk of local contamination. Downsides include the limited sample, inaccessibility of some masses, and variable accuracy, especially in the diagnosis of sarcoma. In regard to FNA of general soft tissue masses, the literature reports a wide range of sensitivities (86%–100%), specificities (36%–100%), and diagnostic accuracies (21.9%–98%)17
LARGE CORE NEEDLE
Because of the limited tissue retrieved with FNA, large core biopsy has evolved as an alternative, using a 10- to 14- gauge coring needle to obtain cylindrical tissue blocks. A block of tissue allows the pathologist to examine tumor architecture and cellular interrelation, improving the diagnosis of histologic subtype and grade compared to FNA. Other advantages of core biopsy, as with FNA, include speed, convenience, decreased cost, minimal morbidity, minimal contamination, and a 0.1% to 1.1% complication rate; disadvantages are also similar to FNA and include limited sampling and inaccessibility of some masses (secondary to size, depth, density, or location). Core biopsy’s soft tissue mass sensitivity ranges from 81.8% to 100%, specificity from 91% to 100%, and diagnostic accuracy from 72.7% to 100%.17
Yang and Damron elegantly compared FNA and core biopsy to each other in the diagnosis of the same soft tissue mass and found core biopsy to be more accurate than FNA on all accounts, with FNA 64% accurate and core 83% accurate in establishing the specific diagnosis.17
Complications from a closed biopsy are mostly related to nondiagnostic procedures. The worst complication includes contamination and interference with future surgical treatment, such as wound hematoma and local tumor spread by passing the needle through the far side of the tumor into normal tissue during the closed biopsy passes.18
SENTINEL LYMPH NODE BIOPSY
The most established population of patients with hand and wrist tumors for which sentinel lymph node biopsy is indicated are those with melanoma of intermediate to high risk of nodal metastasis and clinically negative lymph node basins. The rationale for sentinel lymph node biopsy in melanoma is twofold: first, lymph node status is an important predictor of recurrence and mortality. Second, sentinel lymph node metastases identify patients as candidates for elective lymph node dissection, which prior to this technique was only targeted based on depth of melanoma, rather than occult lymphatic disease.19
Intraoperatively, 1 to 2 ml of vital blue dye (isosulfan blue dye or methylene blue) is injected intradermally at the site of the hand or wrist tumor. The dye is typically combined with a radioactive tracer. After injection, the tissue is gently massaged to facilitate passage of dye into the lymphatics, and after approximately 10 minutes a skin incision can be made at the site(s) of the preoperatively mapped sentinel and in-transit nodes. If a blue-stained lymphatic channel is encountered, it should be carefully dissected and followed to identify the first blue-stained node in the basin. A hand-held gamma probe is invaluable in directing the surgeon, because if a blue node is not easily identified, the probe can provide direction to the sentinel node(s). The “hottest” (highest gamma probe count) node in the basin, blue-colored node(s), and any node with counts above 10% of the hottest node should be removed and labeled as sentinel nodes.20 Compared with full axillary lymph node dissection, the risks of sentinel lymph node biopsy are small.
BIOPSY PREPARATION
All biopsies involve tissue for pathological diagnosis that can be sent as fresh, frozen, and or permanent (formalin) sections. Different specimens require different sections. The most common method of sending a specimen that before surgery is a determinant lesion is permanent section in formalin. This preserves the specimen’s morphological features to permit the pathologist’s histopathological evaluation. Indications for fresh sections include the need for cytogenetic analysis, uric acid crystal analysis and immunohistochemistry to characterize the mass. Fresh sections are also used for evaluation of infection with tissue culture. Frozen section analysis is performed to evaluate for an infectious process and ensure adequate diagnostic tissue has been obtained, but should not be relied upon to diagnose malignant lesions.21
