Biopsy and Mass Removal

Surgical Oncology

Surgery in the management of cancer: diagnosis, cure, palliation of clinical signs, debulking prior to adjunctive therapy, ancillary procedures (placement of a vascular access port and spay/neuter)

Work-Up and Diagnosis of Cancer

History, PE, clinical pathology, diagnostic imaging, tissue sampling, surgery; ways to diagnose the type of cancer: biopsy, surgical removal with histologic examination

Work-Up and Diagnosis of Cancer: History

General history: may suggest presence of cancer, paraneoplastic syndromes; history pertaining to the mass: location, number, duration, size (growing, shrinking, staying the same?); changes in appearance: color, size, ulceration

Work-Up and Diagnosis of Cancer: Physical Examination

Thorough general examination: +/- orthopedic examination, +/- neurologic examination; evaluate local and regional lymph nodes; map location of size and masses: body map

Work-Up and Diagnosis of Cancer: Clinical Pathology

CBC/Chem, urinalysis, other tests depending on differential diagnoses: cytology, other blood tests (ACTH stimulation test or dexamethasone suppression test, ionized calcium, parathyroid hormone panel)

Work-Up and Diagnosis of Cancer: Diagnostic Imaging

Radiographs: affected areas, staging (looking for metastasis; 3-view thoracic radiographs, 2-view abdominal radiographs), contrast studies; ultrasound, computed tomography, magnetic resonance imaging, nuclear scintigraphy

Biopsy of Masses

Indications: treatment will differ depending on tumor (tumor type, tumor behavior such as benign, malignant, aggressive, non-aggressive); planning for surgical resection: margins, prognosis; diagnosis would change owner’s desire to treat

Biopsy of Masses: Techniques

Tissue Sampling Techniques: impression smears, fine needle aspirate

Minimally Invasive Biopsy Techniques: needle core biopsy (tru-cut biopsy, bone biopsy), punch biopsy, image-guided biopsy (using ultrasound or CT)

Surgical Biopsy Techniques: incisional biopsy, excisional biopsy, biopsy via minimally invasive surgery techniques (laparoscopic, thoracoscopic, arthroscopic)

Tissue Sampling/Impression Smear

Press a glass slide against open lesion or cut edge of excised lesion; direct sampling of superficial ulcerated lesions or other exfoliated cells such as TCC in urine

Cheap, noninvasive, no sedation needed, immediate result (preliminary reading), send to pathologist

Technique: blot surface with paper towel, open lesion (press slide firmly against lesion, pull straight up when removing), excised lesion (gently touch surface to glass slide, make several smears on each slide, do not squash/twist/rub tissues on slide)

Fine Needle Aspirate

Easy, minimally invasive, cheap, no sedation needed, low diagnostic yield; 20-22 gauge needle (too big = painful, too small = no cells or lyse cells), 3-5 cc syringe (too big = not enough suction, too small = too much suction gets blood contamination)

Technique: “woodpecker”- needle placed in mass, quickly stab repeatedly, move needle tip direction, DO NOT remove needle from skin until finished, remove syringe and pull plunger back, reattach needle, push plunger down rapidly to squirt cells onto a labeled slide

Suction: needle placed in mass, quickly pull plunger back in 1-2mls, repeat in same spot 3-4 times, if you get blood STOP, DO NOT remove needle from skin until finished, remove syringe and pull plunger back, reattach needle, push plunger down rapidly to squirt cells onto a labeled slide

Minimally Invasive Biopsy/Biopsy Planning

Selection of biopsy site: tract can be excised, center of lesion (internal organs, diffuse lesions); edge of lesion (cutaneous masses, distinct masses on internal organs, include adjacent normal tissue); do not open new tissue planes

Needle Core Biopsy

Indications: no diagnosis with FNA or impression smear, need more tissue for characterization; uses- palpable masses (skin, muscle, bone); organs visible by ultrasound or CT (near body wall, liver or kidney

Soft Tissues: tru-cut biopsy needle (manual, automatic)

Bone: Jamshidi Needle, Michele Trephine

Tru-Cut Needle Biopsy

Methods: percutaneous, intraoperative, ultrasound guided, palpation, blind

Requires sedation or anesthesia

Surgical preparation of site: clip, scrub, sterile gloves

Technique: larger needle, cuts a core of tissue from mass, tissue for histology

Bone Biopsy

Indications: Diagnosis of proliferative or lytic bony lesions, evaluation of bone marrow

Methods: Jamshidi bone biopsy needle (smaller); Michele trephine (larger core, higher risk of pathologic fracture); requires general anesthesia, surgical preparation of site

Technique: locations (proximal humerus, ilial wing, proximal femur, proximal tibia- young dogs only)

Punch Biopsy

Indications: Cutaneous masses, focal organ masses (liver, pancreas, spleen), intestinal biopsies

Instrumentation: baker skin biopsy punch

Technique: planning (sample from edge of lesion- include normal tissue; do not penetrate deeper tissue), sedation or anesthesia, surgical prep, insert perpendicular to surface- rotate to cut, use scissors to release base- gently pick up with thumb forceps

Incisional Biopsy

Indications: large, superficial lesions (ulcerated lesions); lesion is located in area where achieving margins and closure might be difficult; when less invasive techniques fail to yield a diagnosis; type/aggressiveness of tumor would change treatment plan

Excisional Biopsy

Treatment choice unchanged by tumor type- benign tumors/lesions

Lesion is in a place amenable to wider excision if needed

Both diagnosis and treatment

Keys to Obtaining Diagnostic Biopsies

Adequate sample size, number of samples, biopsy junction of normal and abnormal tissues where possible, handle tissue samples gently to avoid artifacts, give pathologist detailed information

Surgical Treatment of Cancer

Best chance to cure cancer is with complete surgical excision THE FIRST TIME

Complete excision cures more patients than any other type of treatment

Margins

The amount of normal tissue removed with the tumor, removal with margins usually indicated- depends on tumor type (1cm for cutaneous carcinomas, 2-3cm for mast cell tumors- 1 fascial plane deep, 3-5cm for cutaneous sarcomas- 1 fascial plane for soft tissue, 2 fascial planes deep for vaccine associated)

No margins needed- benign tumors with low risk of recurrence (lipoma), masses in body cavities

Classification: intracapsular (removal from within capsule or pseudocapsule, debulking; Marginal- removed at margin of tumor (capsule intact, no or little normal surrounding tissue); Wide excision- removed with margin of normal tissue surrounding tumor (fascial planes deep to tumor); Radical excision- removal of entire affected tissue compartment

Contamination of Surgical Site

If capsule entered- lavage surgical field, change gloves, new instruments

Increases risk recurrence

Sample Preparation

Handle tissue gently- do not crush, handling artifacts adversely affect tissue quality and diagnosis

Mark surgical margins- suture, ink (india ink, alcian blue, colored inks)

Painting Margins

Apply to cut surface with cotton tip applicator (do not double dip)

Allow ink to dry (10-20 minutes)

Tissue Fixation

10% formalin, 1 part tissue to 10 parts buffered formalin (penetrates 1cm)

“Bread loaf” tissues > 1cm: allows fixation of all tissues

Separate container for each lesion

Use tissue cassette for very small samples

Labeling

Slides: pencil or slide marking pen, no pen or sharpie (comes off during staining)

Histopathology Jars: write on label +/- lid, use pre-printed patient label

Samples: date, patient name and ID number, location of lesion (cutaneous mass: right forelimb, liver biopsy: left medial lobe, jejunum)

Submission Forms

Patient information: identifying information (name/number), signalment

Complete history

Clinical findings: include gross appearance

Tentative diagnosis

Request margin check if needed

“Junk in = junk out”

Debulking/Palliation

Debulking surgery: removes majority of mass (cytoreduction), intended to follow up with other therapy

Palliative surgery: meant to improve quality of life, not meant for cure or to extend life

Surgery for Metastatic Disease

Used in people for solitary metastasis (lung, liver, brain)

May prolong survival in dogs; ex: removal of metastatic sublumbar lymph nodes in dogs with anal sac adenocarcinoma

Lymph Node Evaluation

Regional lymph nodes should always be assessed for tumor staging (how much of the body is affected), cytologic evaluation by FNA is recommended even if lymph nodes are normal on palpation

Prevention of Cancer

OHE (spay) will reduce the incidence of mammary tumors

Castration can treat/prevent perianal adenomas, testicular tumors (retained testicles) and possibly prostatic adenocarcinoma

Excision of precancerous lesions may prevent progression of disease- squamous cell carcinoma, adenomatous polyps