Faecal Occult Blood Test

Case of the Month (Emma Scurrell May 2013)

Mycobacterial infection in an eye

Enucleation was performed in a 2-year-old male DSH cat that presented with a florid uveitis in the left eye. The eye was blind and retinal detachment was confirmed on ocular ultrasound



Fig 1. There is prominent expansion of the choroid (red arrows) and ciliary body (green arrow) by a grey-white infiltrate. The retina is detached.


Fig 2. H&E section of the globe: the infiltrate consists of florid pyogranulomatous inflammation.
 

Fig 3. Low numbers of acid-fast bacilli (stain red) are identified using a Ziehl-Neelson stain.   







Final Diagnosis

Pyogranulomatous uveitis and retinal detachment associated with mycobacterial infection

Discussion

Mycobacterial infection is an important differential in the case of pyogranulomatous uveitis. Many of these cats will present with a predominant posterior uveitis/choroiditis and associated retinal detachment is common. At the time of presentation, cats with ocular disease may or may not have concurrent signs of systemic disease (e.g. pyogranulomatous to granulomatous panniculitis, pneumonia, arthritis/synovitis or nephritis).

Mycobacteria are not evident on routine H&E-stained sections and special stains (e.g. Ziehl-Neelson) are required for their detection; in addition, the actual number of organisms is frequently very low and a high index of suspicion is helpful to confirm the diagnosis. In order to speciate further, culture of fresh tissue remains the gold standard. PCR can also be performed (on fresh or formalin-fixed tissue) in an attempt to detect the presence of the M.tuberculosis complex (M. tuberculosis, M.bovis and M.microti) or to detect non-tuberculosis mycobacteria (e.g. M.avium, M.fortuitum), however false negatives do occur.

Previous Monthly Cases

Hypertensive Retinopathy January 2010
FIP in a cat - uncommon presentation February 2010
Phaeohyphomycosis    March 2010 
Scleral Rupture April 2010
Canine and feline epulides May 2010
Erythema multiforme in a labrador retreiver June 2010
Keloidal fibrosarcoma in a labrador retreiver July 2010
Cutaneous epitheliotropic lymphoma  August 2010 
Benign cutaneous histiocytoma  September 2010 
Iridociliary adenoma October 2010
Proliferative thrombovascular necrosis of the pinnae November 2010
Signet-ring cell carcinoma in the stomach of a dog December 2010
Cutaneous infiltrative lipoma in a labrador January 2011

Tonsillar squamous cell carcinoma February 2011
Canine orbital meningioma March 2011
"Lung-digit" syndrome in a cat April 2011
Hepatic amyloidosis in a cat May 2011
Haemophagocytic histiocytic sarcoma June 2011
Alternaria spp. infection in an immunocompromised dog July 2011
Ocular manifestation of lymphoma in a cat  August 2011
Kerion dermatophytosis in a Cocker spaniel September 2011
Subcuticular coenurus in a rabbit  October 2011
Optic nerve glioma in a dog November 2011
Malignant transformation of a viral papilloma in a dog  December 2011
Uveodermatological syndrome in an Akita
January 2012
Cutaneous angiostomatosis in a dog  February 2012
Transitional cell carcinoma in a dog  March 2012
Corneal inclusion cysts in a dog   April 2012
Extraskeletal osteosarcoma in a dog  May 2012
Subungual melanoma in a dog  June 2012
Retrobulbar grass seed in a dog   July 2012
Lungworm infection associated with hypercalcaemia in a dog  August 2012
Conjunctival melanoma in a dog  September 2012
Pneumocystis infection in a Cavalier King Charles Spaniel  October 2012
Fungal keratitis and secondary endophthalmitis in a horse November 2012
Myeloid leukaemia with lymph node invasion in a dog    December 2012
Cutaneous toxoplasmosis in a cat   January 2013
Glomerulonephritis in a dog  February 2013
Splenic mast cell tumour in a cat  March 2013
Laryngeal rhabdomyoma in a dog  April 2013



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Faecal Occult Blood Test