Inflammatory pseudotumor of the urinary bladder in dogs: two cases

Pseudotumor inflamatório vesical em cães: dois casos

Dog; inflammatory pseudotumor; blader

Cão; pseudotumor inflamatório; bexiga urinária

Communication

[ Comunicação ]

Inflammatory pseudotumor of the urinary bladder in dogs: Two cases

[Pseudotumor inflamatório vesical em cães: Dois casos]

N.S. Rocha¹, R.A. Tostes², J.J.T. Ranzani¹, F.C. Schmidt³

¹Faculdade de Medicina Veterinária e Zootecnia - UNESP-Botucatu

Distrito de Rubião Jr.

18618-000 - Botucatu, SP

²Serviço de Anatomia Patológica – HV/UNOESTE.

³Instituto de Patologia e Imunologia Molecular da Universidade do Porto-IPATIMUP, Porto - Portugal

Recebido para publicação em 31 de outubro de 2000

Recebido para publicação, após modificações, em 6 de setembro de 2001

e-mail: [e-mail]

Inflammatory pseudotumor of the urinary bladder are tumor-like lesions that clinically, radiologically and histologically simulate a malignant tumor. This group of lesions represents a reaction of urinary bladder to a variety of injurious stimuli and are well characterized in human beings (Lamovecet al., 1992; Kohler et al., 1995). In humans, inflammatory pseudotumors are described at any age but are most common in adolescents and children (Lamovec et al., 1992). In these patients, there is a variety of clinical presentations such as hematuria, dysuria, infection and obstruction of urinary tract. Grossly, these lesions appear as pedunculated intraluminal masses that simulate a malignant tumor. Histologically lesions are composed by fascicles of spindle cells surrounded by variable amounts of collagen fibers, myxoid areas and variable number of inflammatory cells (Hoeffel et al., 1993). There is no report of this condition in small or large animals.

In this report, two cases of inflammatory pseudotumor of the urinary bladder in a 4-year-old mongrel bitch, and in a 8-year-old Dobberman male dog are described. Clinically the animals presented a severe hematuria and abdominal pain. A radiographical exam was conducted of the pelvic region and an opaque multinodular mass at the bladder wall was detected. In one of the cases, a fine needle aspiration cytology was performed which revealed a benign lesion with inflammatory components and some clusters of spindle atypical cells. The cytodiagnosis was suggestive of a pseudotumor. In both cases, a cystotomy for the resection of the masses was performed. Grossly, the masses presented a nodular and polypoid form, measuring 0.6x0.3x0.2cm and 0.4x0.3x0.2cm, respectively, growing up to the vesical lumen.

Histologically the nodule showed proliferation of bundled spindle cells with low grade of atypia and low mitotic index, in a myxoid and inflammatory background (Fig. 1). In both cases, the immunohistochemistry profile was similar, showing diffuse positivity for vimentin (Fig. 2), focal positivity for muscle specific actin and S100 protein (Fig. 3) and negativity for cytokeratin.

The clinical and pathological findings observed in these two pseudoinflammatory tumors occurring in dogs are very similar to those described in human cases (Diez et al., 1997).

According to Mondejar et al. (1996), hematuria is the most important sign of this uncommon lesion and the association with a nodular mass in urinary bladder contributes to confusing with malignant neoplasm. Histologically, Kohler et al. (1995) e Hoeffel et al. (1993) alert that difficulty may arise in differentiating of these lesions from malignant smooth muscle tumors such as low-grade leiomyosarcomas. The immunohistochemistry is helpful to confirm the putative myofibroblastic differentiation of these lesions but would not contribute so much for the differential diagnosis with low grade sarcomas.

The evidences from the literature point that inflammatory pseudotumors are benign lesions and recurrences are extremely rare. This group of lesions should be discriminated from true sarcomas to avoid unnecessary invasive treatments. Only careful histological examination would enable a successful diagnosis. At this time, the follow up of the two dogs (one year) continues without recurrences.

The first two cases of inflammatory pseudotumors of the urinary bladder in dogs are described. No previous report is available in the literature. It is concluded that an adequate diagnosis to recognize benign lesions, based on a good differential diagnosis, should be implemented, in an attempt to avoid the therapeutic consequences of misdiagnosis.

Keywords: Dog, inflammatory pseudotumor, blader

RESUMO

Relata-se a ocorrência de dois casos de pseudotumor inflamatório na bexiga de cães, enfatizando a importância de reconhecer o caráter benigno dessas lesões, evitando uma abordagem terapêutica agressiva como conseqüência de um diagnóstico equivocado.

Palavras-chave: Cão, pseudotumor inflamatório, bexiga urinária.

• DIEZ, R.J.M.; EXTRAMIANA, C.J.; MORA, D.M.J. et al. Bladder pseudosarcoma in pediatrics: clinico-pathological features and treatment. Arch. Esp. Urol., v.50, p.962-970, 1997.
• HOEFFEL, J.C.; DREWS, K.; GASSNER, I. et al. Pseudotumoral cystitis. Pediatr. Radiol., v.23, p.510-514, 1993.
• KOHLER, U.; HORN, L.C.; MEIER, T. et al. Inflammatory pseudotumor of the bladder wall after abdominal hysterectomy for uterine myoma. Zentralbl Gynakol., v.117, p.293-296, 1995.
• LAMOVEC, J.; ZIDAR, A.; TRISINAR, B. et al. Sclerosing inflammatory pseudotumor of the urinary bladder in a child. Am. J. Surg. Pathol., v.16, p.1233-1238, 1992.
• MONDEJAR, R.; MILLAN, I.; RUIZ, L. et al. Eosinophilic cystitis and glandular-cystic cystitis as pseudotumor lesions. Arch. Esp. Urol., v.49, p.179-183, 1996.

Publication Dates

• Publication in this collection
  16 Dec 2002
• Date of issue
  Aug 2002

History

• Received
  31 Oct 2000
• Accepted
  06 Sept 2001