Malignant pilomatricoma

From Dog
Histological appearance of pilomatricomas[1]
Pilomatricoma on the limb of a dog[1]

Malignant pilomatricoma (Pilomatrical carcinoma, Pilomatrix carcinoma) are a cutaneous epithelial cancer characterized by aggressive neoplasic of the hair matrix cells.

Clinically these tumors present as elevated, intradermal masses which vary in size from 1 - 6 cm in diameter. They are usually multilobulated and pigmented, and usually difficult to transect due to bone within the tumor.

These tumors, although locally invasive in the skin of the feet, can spread via lymphatics to peripheral sites[2].

Although normally found on the skin of dogs, metastases to internal organs such as the long bones, lung, liver, spleen[3], vertebrae and pelvic bones[4] have been reported.

Histologically, these tumors appear as irregular islands, lobules, and nests of basaloid cells, which transition abruptly into large lakes of keratinized ghost-cells[5]. Differentiation from basal cell carcinoma may be difficult in some cases.

When diagnosed early, these tumors are usually non-metastatic, and wide excision often resolves the condition.

References

  1. 1.0 1.1 Uni of Pennsylvania
  2. Goldschmidt MH et al' (1981) Malignant pilomatricoma in a dog. J Cutan Pathol 8(5):375-381
  3. da Silva EO et al (2012) Malignant pilomatricoma in a dog. J Comp Pathol 147(2-3):214-217
  4. Jackson K et al (2010) Malignant pilomatricoma in a soft-coated Wheaten Terrier. Vet Clin Pathol 39(2):236-240
  5. Carroll EE et al (2010) Malignant pilomatricoma in 3 dogs. Vet Pathol 47(5):937-943