Superficial tumor removal (skin and subcutaneous tissues)
These tumors…we have a chance to cure!
How often do we get to tell owners that?
The trick is — the first cut is the curing cut.
STAGE THE TUMOR ( TNM) **SEE STAGING CHART AT END**
- Staging a tumor is both the collecting of data and then the recording of that data in a systematic way for consistent prognostication.
- Different tumor types have different staging criteria, but with comprehensive patient data, we can all “be on the same page” when talking about our patient’s tumor stage.
- Examples of common skin/SQ/body wall tumor staging criteria are prepared below as a Wall Chart for easy reference.
- A template for a sticker for your medical record is provided below as well (can be printed on Avery 5126/8126 labels or equivalent.)
(Note the following in patient record.)
- (T) Note characteristics of tumor
- Note location and proximity to other important structures.
- Attachment to overlying skin and/or underlying muscle/fascia
- Inflammation (erythema, edema, pain)
- Ulceration (spontaneous or self-trauma)
- Texture/firmness
- (T) Measure tumor accurately
- Keep a cloth or paper tape-measure or calipers in a handy drawer or by the formalin containers
- Include 3-dimensional measurement if possible
- (N) Examine local/draining lymph nodes
- Enlargement/size/symmetry with opposite?
- Firmness?
- Fixation to underlying tissues?
- Cytology findings? Stick them with needles even if they feel “normal”! Feel and note
- in patient record the following:
- **specify which one(s) are draining the tumor
- 1– submandibular,
- 2– prescapular
- 3– axillary
- 4– abdominal/mesenteric
- 5– inguinal
- 6– popliteal,
- 7– rectal/sublumbar and sacral
- (M) Examine for metastatic foci or other primary
- Chest radiographs
- Abdominal radiographs
- Abdominal ultrasound
- Longbone radiographs
- (G) Histologic grade
- Determined from either needle biopsy, incisional/punch biopsy or excisional biopsy.
DIAGNOSE THE TUMOR TYPE
Always sample tumor such that “track” created can be removed with definitive surgical treatment
Needle aspirate: quick, low morbidity, can be highly diagnostic with good technique (89% sensitivity, 100% specificity)
Goals–
- guide the staging process (i.e. where do we look for LN and metastasis)
- plan the surgical “dose” (i.e. marginal vs. radical resection)
- inflammation vs. neoplastic → if neoplastic, then benign vs. malignant → then if we’re lucky, specific cell of origin
Incisional biopsy: In cases where therapy or surgical dose will be significantly different depending on two different cells-of-origin, consider a low morbidity incisional biopsy.
- Needle biopsy (True-cut needle)
- Biting biopsy (Ronguers or biopsy forceps)
- Punch biopsy (if mass is SQ, incise skin first, then punch)
- Incision biopsy (deep and narrow wedge representing all aspects of mass)
Excisional biopsy: In cases where tumor type is easy to predict, cytology is definitive, and the location and size of tumor will not risk significant surgical morbidity (dehiscence, loss of vital structure, etc.), the diagnosis and definitive treatment can be performed as one procedure.
**Please note: Once a surgical removal is performed, all tissues are forever altered. Incompletely excised tumors seed deeper and wider. The BEST chance for a surgical cure is with the FIRST cut.
**Plan appropriately and advise owners of such!
DETERMINE DEFINITIVE TREATMENT
- Planned marginal resection (benign masses)
- Proportional resection (modified radical resection based on mass diameter)
- Radical “en bloc” resection (malignant or locally aggressive masses)
- Adjunctive radiation therapy (pre or post resection)
- Adjunctive chemotherapy (pre or post resection)
RADICAL “EN BLOC” RESECTION TIPS AND TRICKS
- Two step surgery—
- 1st think about and plan your removal of the mass appropriately
- 2nd think about and plan your closing of the resultant wound
- Cover ulcerated masses prior to surgery with antiseptic-soaked gauze (suture in place)
- 3 cm margin of normal tissue wide and deep to mass is removed with mass (newer data suggests 2cm may be sufficient for some cell types)
- Create the “mass removal wound” first, then adjust the wound to accommodate closure
- “Clean” instruments should never touch mass; “dirty” instruments (that touched mass) should be discarded from field
- Incision must be perpendicular to skin and fascia all the way to the pre- determined depth for removal; cut out a block not a pyramid (It is inappropriate to “bevel” your deep approach; the tumor is 3-dimensional and does not form a nice “apex” in the deep layers.)
- Mark wide and deep margins with metallic clips or steel suture for future identification of internal surgical margins; radiation therapy may only become a strong recommendation after the histologic determination of type and cleanliness of surgical margins. For radiation therapy mapping, radiographs can identify these marked margins more appropriately than guesses based on incision.
- DO NOT assume tumors obey fascial planes!!! If the tumor is adherent to a fascial tissue, a “deep margin” is on the other side of the NEXT fascia plane.
- If a tumor is sitting on or growing into a muscle belly, take a portion of that muscle belly to achieve your deep margins. Doing so is not as big a deal as dirty margins and tumor regrowth! Really.
- It is usually better to get all tumor cells and leave a wound to heal by second intention (or subsequent skin flap/graft) than leave tumor cells to regrow under a closed wound.
HISTOLOGIC PREPARATION
- Stain surgical margins with Alcian blue, India ink or commercial tissue stain (preferably blue, black or yellow)
- (The Davidson Marking System is a handy commercial stain, cheap and easy to purchase online.)
- Partially “bread slice” mass to 1cm thickness to improve fixation
- Preferable submit entire mass; if not feasible, section all compartments of mass,
primarily normal/tumor interface - Provide a 1:10 ratio of tissue to formalin if possible.
- If sending away for diagnosis, save representative sample in house in case of loss.
- And last but most certainly NOT least, submit accurate and detailed gross, clinical pathologic, radiologic, ultrasonographic, CT/MRI, and historical information with mass. (This not a last-minute job for your anesthesia tech; the pathologist needs the details to give you the most accurate and comprehensive diagnostic impression. Take a minute or two and get all that you paid for.)
Lara Rasmussen, DVM, MS
Diplomate, American College of Veterinary Surgeons
DIRECT VETERINARY SURGERY, PC