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Lymphangiosarcoma in Cats
Ann Strieby; Paula Krimer, DVM, DVSc; and Kenneth Latimer DVM, PhD
Class of 2002 (Strieby) and Department of Pathology (Krimer and Latimer), College of Veterinary Medicine, The University of Georgia, Athens, GA 30602-7388
Introduction
Lymphangiosarcoma is a neoplastic disorder of the lymphatic vessels. Tumors of this cell type have been documented in several domestic species (dog,7 cat,5,6,8,10,11 horse3), as well as in people.6 The earliest known record of lymphangiosarcoma in a cat was in a case report published in 1892.10 It is rare, with a reported prevalence as low as 0.06% of all feline neoplasms without an obvious gender or breed predilection.6, 11 This typically aggressive neoplasm is capable of metastasizing to local lymph nodes, lungs, liver, and spleen, as well as infiltrating the neighboring skeletal muscle.6
Clinical Signs
Owners may notice general inappetence or lethargy,10 but more specific clinical signs are variable depending on the primary tumor site.6 Patients may present with an otherwise unexplained chronic lymphedema or regional swelling, particularly in a limb or ventral part of the body.1,3,6,7,11 The edema does not resolve with antibiotic and/or corticosteroid treatment.1,7,11 In cats, the most common site of the primary tumor is in the skin or subcutis of the caudal abdomen.6 Warm, firm masses might be palpated in this region. Cutaneous hemorrhage and ecchymoses (patchy bruising) may be present but difficult to notice underneath unshaven skin. Draining tracts sometimes form from these masses6,11 and self-mutilation has been reported in association with the tumors.10 Less frequently, primary feline lymphangiosarcoma has been found associated with the cranial mesenteric artery or mediastinum.6 Cats with these types of intra-abdominal and intra-thoracic tumors can present with chylous ascites or pleural effusion, respectively, because of lymphatic blockage and abnormal lymph flow.5,6 Peripheral blood values may be normal, however thrombocytopenia and mild to moderate nonregenerative anemia can be found.11 Both leukopenia and leukocytosis have been reported.11 Serum biochemistry findings are nonspecific (see case report, below). Potential sites of metastases include the lungs, spleen, liver, and regional lymph nodes.6,10 Chest radiographs, abdominal ultrasound, and regional lymph node fine needle aspirates should be included for a complete diagnostic evaluation.
Diagnosis
Though cytology can be suggestive of an angiosarcoma, definitive diagnosis requires a surgical biopsy and histopathological evaluation. The cytological specimen shows large, individual stromal cells with indistinct cellular borders in a lipid background. They have abundant, smooth, deeply basophilic cytoplasm with a few small, clear vacuoles. The nuclear to cytoplasmic ratio is moderate, and cells can be multi-nucleated (see Figure 1). Nuclei have finely stippled chromatin with large, prominent, single nucleoli (see Figure 2).
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| Figure 1. Two stromal cells are present in this lipid background, one with trinucleation. There is abundant deeply basophilic cytoplasm with multiple small vacuoles (Wright’s-Giemsa stain with 100x objective). Photograph courtesy of Dr. Kenneth Latimer. |
Figure 2. Notice the prominent nucleolus in the lower cell (Wright’s-Giemsa stain with 100x objective). Photograph courtesy of Dr. Kenneth Latimer. |
Histological samples have profuse, irregular, anastamosing, bloodless vascular channels lined with plump, pleomorphic stromal cells with infrequent mitotic figures (see Figure 3). These tumors can be distinguished from hemangiosarcoma not only because of the conspicuous absence of red blood cells within the channels (see Figure 4), but also because in ultrastructural studies they have gaps in the endothelial cell lining, have fewer pinocytotic vesicles, and lack pericytes.10 Immunohistochemistry using Factor VIII-related antigen can confirm a tumor of endothelial origin, but cannot distinguish between hemangiosarcomas and lymphangiosarcomas.1,6 Some research suggests that lymphangiosarcomas do not stain as intensely with Factor VIII as hemangiosarcomas, but this subjective feature is not a reliable criteria for definitive diagnosis.6
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| Figure 3. There are open vascular channels lined by plump mesenchymal cells with a high nuclear to cytoplasmic ratio (hematoxylin and eosin stain with 40x objective). Photograph courtesy of Dr. Kenneth Latimer. |
Figure 4. The vascular channels lack erythrocytes, which are a prominent feature of other vasoformative neoplasms (hematoxylin and eosin stain with 40x objective). Photograph courtesy of Dr. Kenneth Latimer. |
Etiology
A risk factor or an underlying cause for lymphangiosarcoma in cats has not yet been identified. In humans, chronic edema is considered an important etiologic factor. Women who have radical mastectomy and develop post-operative edema may later develop lymphangiosarcoma in their arms.6 Interestingly, cases of lymphangiosarcoma have not been reported in cats with a history of mammectomy.6 However, this may be a reflection of the generally grave prognosis of feline mammary tumors.6 Some research has suggested a retroviral cause of lymphangiosarcoma in cats, specifically feline leukemia virus (FeLV).10 However, there have been several cases of this tumor in cats that tested negative for FeLV.10 Moreover, an association has not been found between the similar tumor-type hemangiosarcoma and FeLV infections.9
Treatment
There is no specific protocol for the treatment of lymphangiosarcoma in cats. Excessive bleeding has complicated surgical excision of tumors in the caudal abdomen.10 Tumors often recur following attempted excision with frequent metastasis to local lymph nodes.6,10 Many cats are euthanized during or shortly after surgery, especially those with non-cutaneous tumors.6 Survival from time of diagnosis is usually under two months,6 with a maximum reported survival of 10 months.10
References
1. Barnes, J. C., S. M. Taylor, E. G. Clark, D. M. Haines, and S. J. Broughton. 1997. Disseminated lymphangiosarcoma in a dog. Can Vet J 38:42-44.
2. Chun, R. 1999. Feline and canine hemangiosarcoma. Compend Cont Ed 21: 622-652.
3. Fossum, T. W., M. W. Miller, and J. T. Mackie. 1998. Lymphangiosarcoma in a dog presenting with massive head and neck swelling. J Am Anim Hosp Assoc 34:301-303.
4. Gehlen, H. and P. Wohlsein. 2000. Cutaneous lymphangioma in a young Standardbred mare. Equine Veterinary Journal 32:86-88.
5. Gores, B. R., J. Berg, J. L. Carpenter, S. L. Ullman. 1994. Chylous ascites in cats: Nine cases (1978-1993). J Am Vet Med Assoc. 205:1161-1164.
6. Hinrichs, U., S. Puhl, G. R. Rutteman, J. S. Van Der Linde-Sipman, and T. S. G. A. Van Den Ingh. 1999. Lymphangiosarcoma in cats: a retrospective study of 12 cases. Vet Pathol 36: 164-167.
7. Kelly, W. R., G. T. Wilkinson, and P. W. Allen. 1981. Canine angiosarcoma (lymphangiosarcoma): a case report. Vet Pathol 18:224-227.
8. Olgivie, G. K. and A. S. Moore. 1995. Managing the Veterinary Cancer Patient. Veterinary Learning Systems; Trenton, NJ. p. 492.
9. Scavelli, T, A. K. Patnaik, C. J. Mehlhaff, and A. A. Hayes. 1985. Hemangiosarcoma in the cat: retrospective evaluation of 31 surgical cases. J Am Vet Med Assoc. 187:817-819.
10. Swayne, D. E., E. A. Mahaffey, and S. G. Haynes. 1989. Lymphangiosarcoma and Haemangiosarcoma in a Cat. J Comp Path 100: 91-96.
11. Walsh, K. M. and D. P. Abbott. 1984. Lymphangiosarcoma in two cats. J Comp Pathol 94:611-614.
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