ISVD Case Of The Month June 2021

ISVD Case of the Month June 2021Because the histopathological features are not very specific, and the gross features are soremarkable, especially in their localization, we decided to put 2 cases together in this Case ofthe Month submission.Clinical history:The first case is a 1-year-and-7-months old female neutered German shepherd dog which waspresented with a bilateral fluctuating swelling just above the metatarsal foot pads. The swellingswere present since at least 2 weeks. 3-4 ml of serohemorrhagic fluid were extracted bypuncture.Picture 1. Case 1, left hindleg before shaving.

Picture 2. Case 1, left hindleg after shaving

Picture 3. Case 1, right hindleg before shaving

Picture 4. Case 1, right hindleg after shavingThe second case (unrelated to the first one, both in time and location) is a 2 year-old male,intact German shepherd dog presented with bilateral swellings proximally from, and justadjacent to the metatarsal footpads. The lesions were swollen and painful, with draining fluidexuding. Antibiotics (first trimethoprim-sulfonamide, later amoxycillin-clavulanic acid) did notresult in significant clinical amelioration.

Picture 5. Case 2.The lesions of both dogs were biopsied.

Picture 6. Case 2, H&E, 40x.Picture 7: Case 2, H&E, 100x.

Picture 8: Case 2, H&E, 100x, deep dermis and subcutaneous tissue

Picture 9: Case 2, H&E, 200x, deep dermis and subcutaneous tissue

Picture 10: Case 1, H&E, 100x

Picture 11. Case 1, H&E, 100x (Fistula perpendicular to the skin surface).

Picture 12: case 1, H&E, 200xQuestion: What is your top differential?1.2.3.4.5.Sterile granuloma/pyogranuloma syndrome with fistulationDeep pyoderma caused by Staphylococcus pseudintermediusReaction to a perforating foreign bodyFocal metatarsal fistulation of the German shepherd dogFamilial cutaneous vasculopathy of the German shepherd dog

Answer:Signalment:1-year-old female sterilized German shepherd dog, and a 2-year-old intact male Germanshepherd dog.Clinical history:The first case is a 1-year-and-7-months old female neutered German shepherd dog which waspresented with a bilateral fluctuating swelling just above the metatarsal foot pads. The swellingswere present since at least 2 weeks. 3-4 ml of serohemorrhagic fluid were extracted bypuncture.The second case (unrelated to the first one, both in time and location) is a 2 year-old male,intact German shepherd dog presented with bilateral swellings proximally from, and justadjacent to the metatarsal foot pads. The lesions were swollen and painful, draining fluid.Antibiotics (first trimethoprim-sulfonamide, later amoxycillin-clavulanic acid) did not result insignificant amelioration.Question: What is your top differential?Answer:What is your top differential?1. Sterile granuloma/pyogranuloma syndrome with fistulation2. Deep pyoderma caused by Staphylococcus intermedius3. Reaction to a perforating foreign body4. Focal metatarsal fistulation of the German shepherd dog5. Familial cutaneous vasculopathy of the German shepherd dogHistopathologic description:The histopathology of both cases shows similar features. The most severe and extensivechanges are present in the deep dermis and subcutaneous tissue, consisting of a highly cellularinflammatory infiltrate characterized by macrophages, plasma cells, neutrophils, lymphocyteswith subcutaneous cavity formation. A fistular canal (sinus tract) lined by granulation tissuecontaining many plasma cells, lymphocytes, lesser neutrophils and macrophages extends fromthe subcutaneous tissue to the skin surface. Variable fibrosis is present adjacent to theinflammatory infiltrate. The superficial dermis shows a moderate superficial perivascular infiltrateconsisting mainly of plasma cells and lymphocytes. In case 1 superficial dermal fibrosis and lossof hair follicles is present adjacent to the fistular canal. The epidermis is moderately hyperplasticdue to acanthosis. No foreign body material was found within the lesions; PAS and ZN stainsdid not show yeasts, fungi or acid-fast bacteria.

Morphological Diagnosis (both cases): Severe, nodular to diffuse, chronic, deeppyogranulomatous and lymphoplasmacytic panniculitis and dermatitis with fibrosis and fistulaformation.Comments: Focal metatarsal fistulation (also known as deep metatarsal/metacarpal toritis,sterile pedal panniculitis, focal metatarsal sinus tracts) is an uncommon condition most oftenseen in German shepherd dogs, although cases have been described in other breeds such asWeimaraner, Rottweiler, greyhound, Akita Inu and in German shepherd cross-breds. Germanshepherds with direct German ancestry may be predisposed. The age of onset is variable andusually between 1.5 years and 8 years old. Male dogs are far more often affected (ratio male:female 4:1).Typically, the lesions are located bilaterally symmetrically just proximal to both metatarsal footpads. Less frequently, only one hindleg is affected, or the lesions can affect the forelegs in asimilar fashion, proximal to the metacarpal pads. At clinical presentation, a well-definedplantar/palmar deep fistular tract dorsal of the midline of one or multiple paw pads, witherythematous borders discharging serosanguinous to milky fluid is present. In early stages, theepidermis is intact and a rounded, fluid-filled cavity can be felt at palpation. The lesions can beasymptomatic, and only be detected by the owners due to the discharge.Histopathology shows severe, deep nodular to diffuse pyogranulomatous panniculitis and deepdermatitis, with fibrosis and fistular tract formation. In early lesions, neutrophils andmacrophages predominate and discrete pyogranulomas can be observed, whereas theadvanced lesions show diffuse infiltration of neutrophils, macrophages, plasma cells, andlymphocytes. Fibrosis usually is striking, especially adjacent to the intensely inflamed areas. Amilder chronic, mainly plasmacellular inflammation is present in the adjacent, lesser inflamedareas. Although the clinical features and the localization are quite distinctive, the microscopiclesions are not. Therefore, knowledge of the breed and localization of the lesions are crucial forthe pathologist to enable the diagnosis. Special stains may be required to exclude infectiousagents; the lesions should be searched for the presence of possible foreign body material.Concerning the pathogenesis, the low, crouching stance of the German shepherd dog has beenproposed to cause increased strain on the soft tissues of the distal extremities, especially thetendons, fat tissue and paw pads. Antibodies directed against type I and II collagen were foundin affected dogs. Some dogs have concomitant interdigital furunculosis or perianal fistulas;however, German shepherds are predisposed for both conditions.Although spontaneous resolution of the lesion has been described in one case, the conditionusually is persistent. Surgical removal provides only temporary relief, followed by recurrence ofthe lesions. The condition responds fully to anti-inflammatory doses of prednisolone but usuallyrelapses after drug withdrawal. Vitamin E can be used as a glucocorticoid-sparing agent andwas useful as monotherapy in one case in the literature. Topical tacrolimus 0,1% ointment, ortopical 0,01% fluocinolone acetonide in DMSO, or systemic ciclosporin are effective treatmentsfor the condition.

References:1. Kunkle G.A., White S.D. et al., Focal metatarsal fistulas in five dogs. J Am Vet MedAssoc. 1993; 202:756-757.2. Paterson, S., Sterile idiopathic pedal panniculitis in the German shepherd dog; clinicalpresentation and response to treatment of 4 cases. J Small Anim Pract. (1995) 36, 498501.3. Oliveira A.M., Obwolo M.J. et al., Focal metatarsal sinus tracts in a Weimaranersuccesfully managed with ciclosporin, J Small Anim Pract. (2007) 48, 161-164.4. Scholz F.M., Muse R., Burrows A.K. Focal metatarsal fistulae syndrome affecting agreyhound dog succesfully treated with topical 0.1% tacrolimus ointment. Vet Dermatol.(2015) 26, 488-90, e116.5. Bergvall K., Efficacy of topical tacrolimus ointment for treatment of plantar fistulae inGerman shepherd dogs, FC-21, Vet Dermatol. (2004), 15 (Suppl. 1), 27 (abstract).6. Gross T.L., Ihrke P.J., Walder E.J. et al. Diseases of the panniculus. In Skin Diseases ofthe Dog and Cat: Clinical and histopathological diagnosis, 2nd edition, Blackwell2005:553-555.7. Scott D.W., Miller W.H., Griffin C.E. Congenital and hereditary defects. In Muller andKirk's Small Animal Dermatology, 7th ed., Saunders, 2001:985-986.Acknowledgements: Thanks are due to K. Linenborg, Veterinair Centrum Honselersdijk, andN. Vodegel, (at that time working at) Dierenkliniek de Arker, The Netherlands for sending thehistopathological biopsies and for the clinical pictures.Contributor:Nadine Meertens, Veterinary pathologist, Dr.med.vet., Dipl. ECVP

sterile pedal panniculitis, focal metatarsal sinus tracts) is an uncommon condition most often seen in German shepherd dogs, although cases have been described in other breeds such as Weimaraner, Rottweiler, greyhound, Akita Inu and in German shepherd cross-breds. German shepherds with direct German ancestry may be predisposed.