A 4-years old, spayed female, domestic shorthaired cat was presented for a slow growing, non painful, not ulcerated, 1 cm, subcutaneous mass in the dorso-lateral thorax in the site of a previous drug injection (Ranitidine). The cat was in a good body condition, CBC and serum biochemistry were unremarkable. Fine-needle aspirate cytological samples were interpreted by the referring veterinarian as cutaneous lymphoma. Stained and unstained samples were sent for consult. Cytology was characterized by a prevalence of medium sized lymphocytes with round to indented nuclei, finely granular to diffuse chromatin (centrocytes) admixed with small mature lymphocytes, occasional centroblasts and macrophages. Findings were consistent with a chronic lymphohistiocytic dermatitis. To definitely rule out a cutaneous lymphoma the lesion was surgically excised. Histopathology revealed a subcutaneous oval, well demarcated, unencapsulated mass consisting of a mixed inflammatory and reparative reaction containing plump reactive fibroblasts, plasmacells, histiocytes, eosinophils and, occasional mast cells associated with small mature and medium sized reactive lymphocytes either infiltrating the nodule or organized at the periphery in small pseudofollicular and perivascular aggregates. COMMENT: The lesion resembled the so-called vaccine induced cutaneous pseudolymphoma described in man that is characterized by a reactive B cell proliferation associated with abundant histiocytes often in clusters. Pseudolymphoma is a term applied to a group of inflammatory to proliferative lesions that may be misdiagnosed as lymphoma as was in this case by cytology. In cats, arthropod bites and vaccination are probably the main triggers of pseudolymphoma. These lesions are mostly polyclonal (B or T) benign, self-limiting reactions induced by persistent antigenic stimulation. However, in some cases pseudolymphoma may evolve into cutaneous lymphoma.

Injection site reaction (Pseudolymphoma) mimiking a primary cutaneous lymphoma in a cat / A. Forlani, G. Ghisleni, A. Sacchet, M. Caniatti, P. Roccabianca. ((Intervento presentato al 13. convegno ESVCP/ECVCP Congress tenutosi a Dublin nel 2011.

Injection site reaction (Pseudolymphoma) mimiking a primary cutaneous lymphoma in a cat

A. Forlani
Primo
;
M. Caniatti
Penultimo
;
P. Roccabianca
Ultimo
2011-08

Abstract

A 4-years old, spayed female, domestic shorthaired cat was presented for a slow growing, non painful, not ulcerated, 1 cm, subcutaneous mass in the dorso-lateral thorax in the site of a previous drug injection (Ranitidine). The cat was in a good body condition, CBC and serum biochemistry were unremarkable. Fine-needle aspirate cytological samples were interpreted by the referring veterinarian as cutaneous lymphoma. Stained and unstained samples were sent for consult. Cytology was characterized by a prevalence of medium sized lymphocytes with round to indented nuclei, finely granular to diffuse chromatin (centrocytes) admixed with small mature lymphocytes, occasional centroblasts and macrophages. Findings were consistent with a chronic lymphohistiocytic dermatitis. To definitely rule out a cutaneous lymphoma the lesion was surgically excised. Histopathology revealed a subcutaneous oval, well demarcated, unencapsulated mass consisting of a mixed inflammatory and reparative reaction containing plump reactive fibroblasts, plasmacells, histiocytes, eosinophils and, occasional mast cells associated with small mature and medium sized reactive lymphocytes either infiltrating the nodule or organized at the periphery in small pseudofollicular and perivascular aggregates. COMMENT: The lesion resembled the so-called vaccine induced cutaneous pseudolymphoma described in man that is characterized by a reactive B cell proliferation associated with abundant histiocytes often in clusters. Pseudolymphoma is a term applied to a group of inflammatory to proliferative lesions that may be misdiagnosed as lymphoma as was in this case by cytology. In cats, arthropod bites and vaccination are probably the main triggers of pseudolymphoma. These lesions are mostly polyclonal (B or T) benign, self-limiting reactions induced by persistent antigenic stimulation. However, in some cases pseudolymphoma may evolve into cutaneous lymphoma.
Settore VET/03 - Patologia Generale e Anatomia Patologica Veterinaria
Settore VET/08 - Clinica Medica Veterinaria
European Society of Veterinary Clinical Pathology
European College of Veterinary Clinical Pathology
ESVCP
ECVCP
Injection site reaction (Pseudolymphoma) mimiking a primary cutaneous lymphoma in a cat / A. Forlani, G. Ghisleni, A. Sacchet, M. Caniatti, P. Roccabianca. ((Intervento presentato al 13. convegno ESVCP/ECVCP Congress tenutosi a Dublin nel 2011.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/190380
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