Nodule & Draining Tract

Question 1

How is a nodule formed

Answer 1

Cellular infiltrate
Nodule
Draining tract or ulcerated nodule

Question 2

Classifications for N&D tracts

Answer 2

Infectious
Neoplastic
Non infectious

Question 3

Infectious etiologies

Answer 3

Bactieral
1. Deep pyoderma
2. Filamentous bacteria
3. Mycobacteria
Fungal
1. Yeast
2. Filament forming

Question 4

Deep pyoderma

Answer 4

Bacterial furunculosis
Acral lick dermatitis/granuloma
Callus pyoderma
Staph Pseudointermedius** most common cause

Question 5

furunculosis

Answer 5

Common complication of superficial bacterial folliculitis
Draining tracts as a result of rupture of deep inflamed hair follicles - exacerbated by exposure of dermis to follicular contents
May coalesce to form deep ulcers

Question 6

Development of Bactieral Furunculosis

Answer 6

Superficial folliculitis
Deep folliculitis
Furuncle (boil)
Draining tract (furunculosis)

Question 7

Deep vs just infected skin?

Answer 7

Could be localized or generalized
PAINFUL and bleed easy
Recurrent ** usually caused by secondary disease
ALWAYS rule out demodicosis ^^

Question 8

First signs of bacterial furunculosis

Answer 8

PAIN is number 1
Lesions will follow but could be days after pain starts

Question 9

Acral lick dermaitis

Answer 9

Caused by compulsive licking of lower limbs
Underlying diseases reported:
1. Hypersensitivity disorders
2. Joint disease/pain
3. Neuropathy
4. Bacterial or fungal infection (DEEP)
5. OCD

Question 10

Skin lesions of Acral lick dermaitis

Answer 10

Early form: alopecia, erosion, thickening of skin
Chronic form: alopecia & nodule

Question 11

callus pyoderma

Answer 11

Pressure point pyoderma - common in large/giant breeds
Chronic friction leads to obstruction & rupture of hair follicles, localized deep pyoderma develop over elbows & hocks. This can lead to severe cellulitis

Question 12

Skin lesions of callus pyoderma

Answer 12

Mild: alopecia and thickening of skin
Severe: alopecia and draining tracts

Question 13

Deep pyoderma DX and Tx

Answer 13

Treat like a superficial EXCEPT
1. When systemic abx are required not only topical
2. Systemic abx should be continued beyond two weeks of clinical resolution**
3. Selection should be based off c/s esp for recurrent cases

Question 14

Non infectious etiologies

Answer 14

Juvenile cellulitis
Interdigital Comedones & cysts
Canine perinatal fistula
Idiopathic nodular Panniculitis
Foreign body granuloma

Question 15

Juvenile cellulitis

Answer 15

Unknown cause, vaccination reactions??
Puppies 3weeks-4months, no breed disposition
Acute onset, +/- vaccination, alert vs dull/lethargic

Question 16

Lesions of juvenile cellulitis

Answer 16

Skin lesion
- swollen muzzle, eyelids, lips
-24-48hrs: papules, pustules
-at presentation: draining tracts, pus, crust
Other signs:
- lymphadenopathy, +/- fever

Question 17

Tx of juvenile cellulitis

Answer 17

Immunosuppressive doses of GS’s
- prednisone
- dexamethasone
Tx lasts 2-3 weeks, systemic antibiotics if suspect 2nd infection but prognosis is good

Question 18

Interdigital Comedones & cysts

Answer 18

Common in large/giant breeds - bowed elbows or hocks
Caused by external surface trauma/friction of interdigital hair = plugged hair follicles

Question 19

Pathogenesis of interdigital Comedones and cyst

Answer 19

Trauma forces hair into skin of digits
Leads to secondary follicles (cystic) which forms as a primary follicle (cystic)
Cyst will rupture on the dorsal surface of the skin and develop a draining tract

Question 20

Features of interdigital Comedones and cyst

Answer 20

Anatomical problem - cannot be cured w out surgery
Lesions present as hyperkeratosis on ventral paw pad and ulcerative lesions with draining tracts on dorsal surface

Question 21

Underlying disease that could mimic interdigital cysts

Answer 21

1. Atopic dermatitis - allergy /licking of paws
2. Pedal demodicosis -
3. Deep bacterial & fungal infection

Question 22

Canine perinatal fistula

Answer 22

Common in German shepherds
Draining tracts, multiple sinuses, ulcers in perianal region
Supposed pathogenesis:
- excessive T cell mediated inflammation
- abnormal macrophage activation
- food reaction?
Licking & pain are common signs

Question 23

Treating CPF

Answer 23

Medical - life long
Cyclosporine
Topical tacrolimus
Antibiotics
Azathioprine

Question 24

Fluorescent light therapy for CPF

Question 25

Neoplastic nodules etiology

Answer 25

Lipoma*
Histocytoma*
Sebaceous adenoma*
Mast cell tumor
Cutaneous lymphoma
Basal cell tumor
Plasma cell tumor

Question 26

Lipoma

Answer 26

Benign neoplasia from subQ fat cells
Common in dogs - rare in cats
Easy to palpate, soft, well demarcated
Might not stain - alcohol dissolves fat

Question 27

Tx of lipoma

Answer 27

Surgical excision
Some can be infiltrative and require radical surgical excision to prevent local recurrence

Question 28

Histocytoma

Answer 28

Benign caused by histiocytes (antigen presenting cells)
Common in young dogs <3y
Usually presents as a single lesion - head. Pinnae, limbs
Firm alopecia I nodule - self limiting

Question 29

Sebaceous adenoma

Answer 29

Benign arising from sebaceous gland cells
Common in older dogs
Common on eyelids, trunk and limbs
Can leave, remove or freeze it off

Question 30

Mast cell tumor

Answer 30

Malignant and aggressive tumors
Dogs - arise in dermis or subQ
Cats - arise form dermis, spleen, liver or visceral lymph
Usually just only lesion, can pop up anywhere and look like anything …

Question 31

DX mast cell tumors

Answer 31

FNA cytology - round cells, nuclei, basophilic intracytoplasmic granules

Question 32

Tx mast cell tumors

Answer 32

Aggressive & wide surgical excision - clean margins
Radiation therapy
Chemotherapy
Tyrosine kinase inhibitors