Draining sinus tracts 1 Flashcards
What is a sinus?
What is a fistula?
What fistulas are dealt with in dermatology?
Sinus = tract from skin surface to a deeper, but abnormal, focus, usually in the dermis or subcutis
Fistula = tract between two epithelium-lined structures (e.g. skin and a hollow organ)
Dermatology fistulas:
* Anal furunculosis – sometimes referred to (inaccurately) as ‘perianal fistulae’ - actually are sinuses!
* Fistulae of the feet – tract between the dorsal and palmoplantar aspects of the foot
What are the 4 ways material reaches the dermis/subcutis?
Give the commom examples in each category:
Why does a drainign tract then form?
a. Penetration from surface
* e.g. foreign body, mycobacterial/ opportunistic fungal infections
b. Breakdown of the hair follicle (furunculosis)
e.g.
* deep pyoderma
* demodicosis
* dermatophytosis
c. Systemic routes
* e.g. systemic mycoses
d. Formed within skin
* e.g. immune-mediated/autoimmune
Material sets up an inflammatory/foreign body reaction –> bulla –> ruptures –> draining tract
What things are you thinking about when investigating a draining sinus?
- Site of lesion
- Solitary/multifocal
- Palpable underlying nodule?
- Nature of exudate
- Lifestyle of patient
- Other clinical signs (dermatologic/systemic)
Warning - Some conditions zoonotic (e.g. mycobacteria, fungi) - assume all are infectious until proven otherwise! Clearly state d/d on lab forms so lab staff can assess risk
What diagnostics can you do on draining sinuses and why would you do them?
**Cytology of exudate **
FNA from bulla, if present
Touch impression of sinus tract contents
Deep skin scrapes/hair plucks – if demodicosis suspected
Biopsy for histopathology and tissue culture – frequently required
microbial culture
* Tissue culture best – tissue with drop of sterile saline in sterile universal container
* If tissue grains present in exudate, submit for culture also – often many organisms!
How do you do biopsy for histopathology and tissue culture for draining sinuses?
- Do not shave or cleanse first
- Biopsy erythematous skin adjacent to tract and go deep enough to include dermis and subcutis – need wedge, not punch. Multiple samples/locations.
- May need special stains (e.g. for mycobacteria, Actinomyces, Nocardia, fungi) – notify pathologist of your d/ds
What are you going to ask the lab for when wanting a microbial culture for draining sinuses?
Aerobic + anaerobic bacterial culture
Fungal culture (not just dermatophytes)
What (other thing) do you need to do do if you are submitting a biopsy tissue sample for histopatholgy from a cutaneous/subcutaneous mass in a cat?
Freeze fresh tissue samples when submitting biopsies for histopathology from any cutaneous/subcutaneous mass in a cat!
* Mycobacteria very hard/slow to grow - can do mycobacterial PCR on fresh frozen tissue
A 7-year-old FN GSD presents with multiple sinus tracts around the anus. The area is painful and she is exhibiting dyschezia. The dog is otherwise well, except for a lifelong tendency to colitis
- What is your top differential diagnosis?
- What is its cause?
- What will you do next to more fully assess the extent of the problem?
- Establish what management options are available, so that you can discuss these with the owner. What are their pros and cons?
What is your top differential diagnosis?
Anal furunculosis
What is its cause?
non-infectious, immune mediated with genetic predisposition, immune system reacts to normal bacteria of anus
What will you do next to more fully assess the extent of the problem?
physical exam including digital rectal examination, is a primary means of diagnosis of perianal fistula. Other causes of fistulization (eg, anal sac disease, neoplasia) need to be ruled out. Bacterial culture to identify organisms causing secondary infection may be needed. Tissue biopsy is rarely indicated.
Establish what management options are available, so that you can discuss these with the owner. What are their pros and cons?
Oral ciclosporin at a dose of 5– 10 mg/kg q24h is the initial treatment
◦ Immunosuppressive
some does will go into remission in 8-12 weeks
- also need to address colitis
- stool softener for dyschezia
Once large fistulas are controlled, the addition of topical tacrolimus 0.1%, a related calcineurin inhibitor, may be an effective adjunctive or maintenance treatment
◦ Immunosuppressive
A 5-year-old DSH cat presents with lethargy, inappetence and multiple painful deep cutaneous nodules, some with draining tracts to the skin. The patient has no prior history of problems but is a fussy eater and will only eat canned tuna.
What is your top differential diagnosis?
What is the cause of this condition?
How will you confirm your diagnosis?
How will you manage the condition?
What will you advise about the risk of other cats in the household becoming similarly affected?
What is your top differential diagnosis?
Pansteatitis
What is the cause of this condition?
a sterile, inflammatory condition of the fat that is caused by insufficient dietary vitamin E and/or excessive dietary unsaturated fatty acids. The inadequate vitamin E:unsaturated fatty acid ratio results in oxidative damage to adipocytes and subsequent lipid peroxidation. Cats that eat a fish only diet are at increased risk of developing this disease.
How will you confirm your diagnosis?
The dietary history and clinical signs will strongly suggest pansteatitis. However, a skin biopsy (being careful to include adipose tissue in the biopsy) with special stains for infectious agents is necessary to confirm the diagnosis and rule out infectious causes of inflammation of the fat. Plasma tocopherol levels of < 300 mg/100 ml further confirm the diagnosis.
How will you manage the condition?
Supportive care, IVFT, pain relief
* Affected cats should be fed a high-quality, properly balanced diet.
* Additional α -tocopherol supplementation (50 mg/kg po q24 h) may also be helpful to speed recovery.
* Full recovery may take several weeks. It is imperative that affected cats continue to consume a balanced diet even after resolution of clinical
What will you advise about the risk of other cats in the household becoming similarly affected?
Not infectious - at higher risk of developing it if they are fed the same diet, cats have different level of tolerance of vitamin E:unsaturated fatty acid ratio, so even if fed the same diet they might not get it or might get it at a different time
A 6-year-old GSD presents with a well-demarcated sinus tract in the midline plantar metatarsus, just proximal to the metatarsal pad of both hind feet.
A serosanguinous exudate is seen but the area does not appear painful, and the patient is not lame. There is no palpable underlying nodule, and the dog is systemically well. No other skin lesions are found.
What is your top differential diagnosis?
What is the possible cause of this condition?
How will you manage the condition and what is the long term prognosis?
**What is your top differential diagnosis? **metatarsal fistulation
What is the possible cause of this condition?
Unknown but circulating antibodies to type 1 and 2 collagen are elevated in some dogs
How will you manage the condition and what is the long term prognosis?
Cycclosporin 5mg/kg per day
Topical tacrolimus 0.1%
Be aware this is a condition typically controlled but not cured, needs long term medication to keep under control
