Angiolipoma

From Dog
An angiolipoma composed of lobules of mature adipocytes admixed with blood vessels[1]

Angiolipoma, angiofibrolipoma and infiltrative angiolipoma are benign cutaneous neoplasms of canine adipose tissue[2].

Angiolipomas are usually a solitary subcutaneous nodule composed of thin-walled blood vessels randomly distributed throughout lobules of well-differentiated adipose tissue.

They are commonly reported in the subcutis on the trunk of older dogs, but may occur in other regions such as the epidural lumbar region[3] and salivary gland[4]. Tenderness associated with manipulation of these tumors may help distinguish them from lipomas which are usually non-painful.

These are histologically and morphologically distinct from the more common lipoma which lack the vascularity and fibrous tissue content of angiolipomas.

These tumors should be distinguished histologically from nodular hyperplasia, nevus, hamartoma, hemangiomas and hemangiosarcomas. Positive staining by Masson’s trichrome method and/or negative immunohistochemical staining for smooth muscle actin allow for easy differentiation of an angiofibrolipoma from an angiolipoleiomyoma.

Distinguishing an angiolipoma that has sparse vascularity from a simple lipoma or a highly vascular angiolipoma from a hemangioma infiltrating adipose tissue could both present a diagnostic challenge.

The presence of large vessels not normally seen in lipoma and absence of nerves normally seen in adipose tissue are features that may allow differentiation[5].

Complete surgical excision is usually curative.

References

  1. Liggett AD et al (2002) Angiolipomatous tumors in dogs and a cat. Vet Pathol 39(2):286-289
  2. Hendrick MJ et al (1998) Histological Classification of Mesenchymal Tumors of Skin and Soft Tissues of Domestic Animals, 2nd series, vol. II, pp. 19 and 43. Armed Forces Institute of Pathology, Washington, DC
  3. Reif U et al (1998) Extradural spinal angiolipoma associated with bone lysis in a dog. J Am Anim Hosp Assoc 34(5):373-376
  4. Kitshoff AM et al (2010) Infiltrative angiolipoma of the parotid salivary gland in a dog. J S Afr Vet Assoc 81(4):258-261
  5. Gross TL et al (1992) Veterinary Dermatopathology: A Macroscopic and Microscopic Evaluation of Canine and Feline Disease, pp:430–433. Mosby Year Book, St. Louis, MO