Nodule & Draining Tract Flashcards
How is a nodule formed
Cellular infiltrate
Nodule
Draining tract or ulcerated nodule
Classifications for N&D tracts
Infectious
Neoplastic
Non infectious
Infectious etiologies
Bactieral
1. Deep pyoderma
2. Filamentous bacteria
3. Mycobacteria
Fungal
1. Yeast
2. Filament forming
Deep pyoderma
Bacterial furunculosis
Acral lick dermatitis/granuloma
Callus pyoderma
Staph Pseudointermedius** most common cause
furunculosis
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
Development of Bactieral Furunculosis
Superficial folliculitis
Deep folliculitis
Furuncle (boil)
Draining tract (furunculosis)
Deep vs just infected skin?
Could be localized or generalized
PAINFUL and bleed easy
Recurrent ** usually caused by secondary disease
ALWAYS rule out demodicosis ^^
First signs of bacterial furunculosis
PAIN is number 1
Lesions will follow but could be days after pain starts
Acral lick dermaitis
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
Skin lesions of Acral lick dermaitis
Early form: alopecia, erosion, thickening of skin
Chronic form: alopecia & nodule
callus pyoderma
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
Skin lesions of callus pyoderma
Mild: alopecia and thickening of skin
Severe: alopecia and draining tracts
Deep pyoderma DX and Tx
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
Non infectious etiologies
Juvenile cellulitis
Interdigital Comedones & cysts
Canine perinatal fistula
Idiopathic nodular Panniculitis
Foreign body granuloma
Juvenile cellulitis
Unknown cause, vaccination reactions??
Puppies 3weeks-4months, no breed disposition
Acute onset, +/- vaccination, alert vs dull/lethargic
Lesions of juvenile cellulitis
Skin lesion
- swollen muzzle, eyelids, lips
-24-48hrs: papules, pustules
-at presentation: draining tracts, pus, crust
Other signs:
- lymphadenopathy, +/- fever
Tx of juvenile cellulitis
Immunosuppressive doses of GS’s
- prednisone
- dexamethasone
Tx lasts 2-3 weeks, systemic antibiotics if suspect 2nd infection but prognosis is good
Interdigital Comedones & cysts
Common in large/giant breeds - bowed elbows or hocks
Caused by external surface trauma/friction of interdigital hair = plugged hair follicles
Pathogenesis of interdigital Comedones and cyst
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
Features of interdigital Comedones and cyst
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
Underlying disease that could mimic interdigital cysts
- Atopic dermatitis - allergy /licking of paws
- Pedal demodicosis -
- Deep bacterial & fungal infection
Canine perinatal fistula
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
Treating CPF
Medical - life long
Cyclosporine
Topical tacrolimus
Antibiotics
Azathioprine
Fluorescent light therapy for CPF
Neoplastic nodules etiology
Lipoma*
Histocytoma*
Sebaceous adenoma*
Mast cell tumor
Cutaneous lymphoma
Basal cell tumor
Plasma cell tumor
Lipoma
Benign neoplasia from subQ fat cells
Common in dogs - rare in cats
Easy to palpate, soft, well demarcated
Might not stain - alcohol dissolves fat
Tx of lipoma
Surgical excision
Some can be infiltrative and require radical surgical excision to prevent local recurrence
Histocytoma
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
Sebaceous adenoma
Benign arising from sebaceous gland cells
Common in older dogs
Common on eyelids, trunk and limbs
Can leave, remove or freeze it off
Mast cell tumor
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 …
DX mast cell tumors
FNA cytology - round cells, nuclei, basophilic intracytoplasmic granules
Tx mast cell tumors
Aggressive & wide surgical excision - clean margins
Radiation therapy
Chemotherapy
Tyrosine kinase inhibitors
