Misty Grey

Below is the text of the biopsy report.  As I said in a comment, I don’t understand all the nitty gritty stuff yet, but I will be talking it over with my vet and the oncologist.  The upshot is, the amputation should be curative.  No chemo/radiation ordeal to dread.

It sounds like the tumor had gone into the bone of her leg worse than we saw initially on the Xrays, and it said they compress the muscle too – how in the world was my poor Misty not in pain?  I worry that maybe she was, and she was just hiding it or ignoring it.  I’ve seen her in pain in the past though – a few years ago her ears were really messed up due to food allergies, and at first we thought it was ear mite and were treating them accordingly.  They got more and more gunked up, we were giving her ear mite meds and cleaning her ears, and she hated it, and it wasn’t getting better.  When I moved a few years ago I switched vets, and it was the new vet who diagnosed it as food allergies, cleaned her ears up and got her on hypoallergenic food.  But when they were really bad I could tell it hurt because when I was petting her she would headbutt my hand or an object and accidentally bump her ears sometimes, and whenever that happened she would shy away and then go hide somewhere.  She hasn’t acted at all like there is any problem with her leg.  She even clawed the scratcher, stretched, kneaded her blankets, ran, jumped, played… etc.  Not even any sign it was impairing the movement of her muscles.

I think A1 was the tumor’s main body on the outside of her leg.  A2 was, I assume, the part that went into her bone.  And B is the lymph node.

Microscopic Description:

A1: Multilobular proliferation of mildly pleomorphic neoplastic spindle cells arranged in perivascular whorls and solid interwoven bundles are seen. Neoplastic spindle cells have mildly pleomorphic medium oval vesicular nuclei and a small amount of eosinophilic fibrillar cytoplasm. Neoplastic cells are associated with a variable amount of fine granular basophilic extracellular matrix and variably thick collagen bundles. Interwoven fascicles of disorganized neoplastic spindle cells with minimally pleomorphic elongate flattened nuclei are also seen. Mitotic count is approximately 3 per 10 high power fields. The minimally to mildly pleomorphic neoplastic spindle cells are associated with in rare band of densely packed mildly pleomorphic neoplastic spindle cells. Neoplastic spindle cells compress skeletal muscle and in one area extend into the interstitium of the skeletal muscle.

A2: Similar proliferation of mildly pleomorphic neoplastic spindle cells arranged in concentric perivascular whorls are seen. Neoplastic cells infiltrate skeletal muscle. Multiple mildly degenerate peripheral nerves are seen. Multifocal chronic inflammation is associated with neoplastic infiltration of the skeletal muscle adjacent to the peripheral nerves. Tiny multiple fragments of dark mineralized bone are present at one cut edge of the skeletal muscle.

B: Single peripheral lymph node is examined. Perinodal adipose tissue contains numerous small lymphocytes intermixed with scattered fewer but moderate numbers of plasma cells and small numbers of macrophages. Subcapsular sinus and the medullary sinus contains small numbers of hemosiderin laden macrophages. Diffuse mild edema is present.

Microscopic Interpretation: Peripheral nerve sheath tumor with atypical fibroblasts.  Mild drainage reaction, lymph node.

(Biopsy) Comments: Majority of the sample is consistent with peripheral nerve sheath tumor. Peripheral nerve sheath tumors are less common in the cat compared to the number of case diagnosed in dogs. Feline peripheral nerve sheath tumors (PNST) similar to canine PNST have moderate potential for recurrence at the sample site but low metastatic potential.

It can be difficult to distinguish reactive fibroblasts and hypertrophied endothelial cells from their malignant counterparts.

Re-examination of the sample site is recommended.