JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

November 2016

I-N18

 

Slide A

Signalment (JPC # 1647900):  Age and breed unspecified, dog

HISTORY:  A slow growing soft subcutaneous mass

HISTOPATHOLOGIC DESCRIPTION:  Haired skin, subcutis:  Expanding the subcutis and compressing the underlying skeletal muscle, is a 1.5 cm diameter, well-circumscribed, partially encapsulated, moderately cellular neoplasm composed of mature adipocytes on a fine fibrillar stroma.  Neoplastic adipocytes have distinct cell borders and a single 60-130 micron clear vacuole that compresses and peripheralizes the nucleus.  Nuclei are flattened and hyperchromatic.  Anisocytosis is marked depending on the size of the vacuole, but anisokaryosis is minimal.  Mitoses are not seen.  There are two focal areas of hemorrhage within the neoplasm with associated dark brown to golden globular pigment (hemosiderin).

MORPHOLOGIC DIAGNOSIS:  Subcutis:  Lipoma, breed not specified, canine.

Slide B

Signalment (JPC # 1958368):  Age and breed unspecified, dog

HISTORY:  A large, soft, subcutaneous mass

HISTOPATHOLOGIC DESCRIPTION:  Haired skin, subcutis, and panniculus carnosus:  Expanding the subcutis; elevating the overlying dermis and epidermis; widely separating adnexa; and separating, surrounding, and replacing skeletal muscle bundles is a poorly circumscribed, infiltrative neoplasm composed of densely packed adipocytes with distinct cell borders and a single, clear, 50-80 um cytoplasmic vacuole that compresses and peripheralizes the nucleus.  Nuclei are flattened and hyperchromatic.  Mitoses are not observed.  Multifocally, apocrine glands are mildly ectatic.  Skeletal muscle bundles are multifocally mildly atrophied characterized by disorganization of myofibers with paler staining.

MORPHOLOGIC DIAGNOSIS:  Haired skin, subcutis:  Infiltrative lipoma, breed not specified, canine.


Slide C

Signalment (JPC #1900656):  Age and breed unspecified, dog

HISTORY:  A firm subcutaneous mass from the shoulder

HISTOPATHOLOGIC DESCRIPTION:  Haired skin and subcutis, shoulder:  Effacing the subcutis, elevating the overlying dermis, and extending to the deep margins, is an infiltrative, unencapsulated, multilobulated neoplasm composed of polygonal to spindle cells that are solidly cellular or arranged in short streams separated by a fine fibrovascular stroma.  Neoplastic cells have indistinct cell borders and a moderate amount of eosinophilic cytoplasm that often contains one large (up to 80 um) distinct, clear vacuole (lipocyte) or several small (10-15 um) distinct vacuoles (lipoblast).  Nuclei are round to oval, vesiculate and occasionally centrally located, with a single prominent magenta nucleolus.  Mitoses average 2 per 10 400X HPF.  There is marked anisokaryosis and anisocytosis.  The center of the neoplastic lobule is necrotic.  Multifocally there is mild hemorrhage admixed with few hemosiderin-laden macrophages.  

MORPHOLOGIC DIAGNOSIS:  Haired skin and subcutis, shoulder (per contributor):  Liposarcoma, breed not specified, canine.

GENERAL DISCUSSION:

Lipoma

Infiltrative Lipoma

Liposarcoma

Pathogenesis:

Other Lipocytic tumors:          

Lipomatosis

Fibrolipoma

Angiolipoma

Angiofibrolipoma

Chondrolipoma

Spindle cell lipoma

Atypical lipoma

Myxoid liposarcoma

Pleomorphic liposarcoma

Intracranial lipomatous hamartoma

TYPICAL GROSS FINDINGS:

Lipoma

Infiltrative Lipoma

Liposarcoma

TYPICAL LIGHT MICROSCOPIC FINDINGS:

Lipoma

Liposarcoma

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

    1. Avallone G, Pellegrino V, Roccabianca P, Lepri E, Crippa L, Beha G, De Tolla L, Sarli G. Tyrosine kinase receptor expression in canine liposarcoma. Vet Pathol 2016 Oct 3. pii: 0300985816671379. [Epub ahead of print]
    2. Avallone G, Roccabianca P, Crippa L, Lepri E, Brunetti B, Bernardini C, Forni M, Olandese A, Sarli G. Histological classification and immunohistochemical evaluation of MDM2 and CDK4 expression in canine liposarcoma. Vet Pathol. 2016: 53(4)773-780.
    3. Chum HH, Long CT, McKeon GP, Chang AG, Luong RH, Albertelli MA. Abdominal lipomatosis with secondary strangulation of masses in an adult rhesus macaque (Macaca mulatta). Comp Med. 2014;64(5)404-408.
    4. Deitz J, Heckers KO, Aupperle H, Pees M. Cutaneous and subcutaneous soft tissue tumours in snakes: A retrospective study.  J Comp Path. 2016;155(1):76-87.
    5. Dennis MM, McSporran KD, Bacon NJ, Schulman FY, Foster RA, Powers BE. Prognostic factors for cutaneous and subcutaneous soft tissue sarcomas in dogs. Vet Pathol. 2011;48(1):73-84.
    6. Doria-Torra G, Martinez J, Domingo M, Vidana B, Isidoro-Ayza M, Casanova MI, Vidal E. Liposarcoma in animals: Literature review and case report in a domestic pig (Sus scrofa).  J Vet Diag Invest.  2015:27(2)196-202.
    7. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell; 2005: 766-777.
    8. Hardistry JF, Elwell MR, Ernst H, et al. Histopathology of hemangiosarcomas in mice and hamsters and liposarcomas/fibrosarcomas in rats associated with PPAR agonists. Toxicol Pathol. 2007;35(7):928-941.
    9. Hendrick MJ, Mahaffey EA, Moore FM, Vos JH, Walder EJ. Histological classification of mesenchymal tumors of skin and soft tissues of domestic animals. Washington, DC: Armed Forces Institute of Pathology, American Registry of Pathology, and The World Health Organization Collaborating Center; 1998: 19-20.
    10. Kwon HJ, Park MS, Kim DY, Cho DY, Yoon BI, Shin NS, Kim DY. Round cell variant of myxoid liposarcoma in a Japanese macaque (Macaca fuscata). Vet Pathol. 2007;44(2):229-232.
    11. Mauldin EA, Peters-Kennedy J. Integumentary system.  In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. New York, NY: Elsevier Limited; 2015:726.
    12. Plumlee QD, et al., High-grade myxoid liposarcoma (round cell variant) in a dog, J Comp Pathol. 2016 Sep 21. pii: S0021-9975(16)30110-4. [Epub ahead of print]
    13. Pervin M, Izawa T, Ito S, Kuwamura M, Yamate J. Metastatic liposarcoma in a South African fur seal (Arctocephalus pusillus).  J Comp Pathol. 2016:155(1):72-75.
    14. Sickinger M, Wasieri J, Koehler K, Doll K, Reinacher M. Congenital infiltrative lipomas in a calf. J Vet Diag Invest. 2009;21(5):719-721.
    15. Scott DW, Miller WH, Griffin CE. Neoplastic and non-neoplastic tumors. In: Muller & Kirk's Small Animal Dermatology, 6th ed. Philadelphia, PA: WB Saunders Co; 2001: 1308-1312.
    16. Scott SJ, Elliot K, Philibert H, Summers BA, Godson D, Singh B, Simko E. An unusual lipomatous brain mass in a golden retriever dog.  J Vet Diag Invest. 2015;27(6)772-776.
    17. von Bomhard W, Goldschmidt, MH, Shofer FS, Peri L, Rosenthal KL, Mauldin EA. Cutaneous neoplasms in pet rabbits: A retrospective study. Vet Pathol. 2007;44(5):579-588.
    18. Wagner KD, Benchetrit M, Bianchini L, Michiels JF, Wagner N.  Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is highly expressed in liposarcoma and promotes migration and proliferation. J Pathol. 2011;224(4):575-588.


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