JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

October 2016

I-N11

 

Signalment (JPC #1946348): Adult Sprague-Dawley rat 

HISTORY:  A 4 x 4 x 3 cm mass was present on the right external ear canal and right side of the head.  On cut surface, it consisted mainly of a yellowish friable material with occasional cystic spaces.

HISTOPATHOLOGIC DESCRIPTION:  Zymbal’s gland:  Infiltrating subcutaneous tissue is a well-circumscribed, unencapsulated, multilobulated neoplasm that forms variably-sized cystic spaces.  The neoplasm is composed of polygonal cells arranged in islands and trabeculae supported by a moderate fibrovascular stroma.  Neoplastic islands often have a peripheral layer of basaloid reserve cells which have distinct cell borders, a small amount of eosinophilic, granular cytoplasm, round to oval nuclei with finely stippled chromatin and up to 4 distinct nucleoli; anisocytosis and anisokaryosis are mild and mitoses are 2/10 HPF. Mitotic figures are present both within basal cells and more mature sebocytes. Neoplastic cells exhibit both sebaceous and ductal (squamous) differentiation. Multifocally within the neoplasm, there are variably-sized areas of cystic degeneration (dilated ducts), characterized by cystic spaces filled with viable and degenerate neutrophils, eosinophilic granular material (sebum), cocci and/ or necrotic debris.  Multifocally the neoplasm is infiltrated by numerous viable and degenerate neutrophils, epithelioid macrophages and scattered multinucleated giant cells admixed with acicular cholesterol clefts (pyogranulomatous inflammation) or aggregates of lymphocytes and plasma cells.

MORPHOLOGIC DIAGNOSIS:  Zymbal’s gland:  Carcinoma, Sprague-Dawley rat, rodent.

SYNONYMS:  Carcinoma of the auditory sebaceous gland

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: John Wiley and Sons, Inc. 2016: 164.
  2. Copeland-Haines D, Eustis SL. Specialized sebaceous glands. In: Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds. Pathology of the Fischer Rat: Reference and Atlas. San Diego: Academic Press; 1990: 279-288.
  3. Reznik GK: Auditory sebaceous gland (Zymbal's gland). In: Stinson SF, Schuller HM, Reznik GK, eds. Atlas of Tumor Pathology of the Fischer Rat. Boca Raton, FL: CRC Press; 1990: 379-393.
  4. Rudman D, Cardiff R, Chouinard L, Goodman D, Kuttler K, Marxfeld H, Molinolo A, et al. Proliferative and nonproliferative lesions of the rat and mouse mammary, Zymbal’s preputial and clitoral Glands. Toxicol Pathol. 2012 (40); 7S-39S.
  5. Seely JC. Adenoma of the auditory sebaceous glands. In: Jones TC, Mohr U, Hunt RD, eds. Monographs on Pathology of Laboratory Animals: Eye and Ear. Washington, DC: International Life Sciences Institute; 1989:143-145.
  6. Seely, JC. Auditory sebaceous glands (Zymbal's glands). In: Mohr U, Dungworth DL, Capen CC, eds. Pathobiology of the Aging Rat. Vol 2. Washington, DC: ILSI Press; 1994;423-433.
  7. Seely JC. Carcinoma of the auditory sebaceous glands. In: Jones TC, Mohr U, Hunt RD, eds. Monographs on Pathology of Laboratory Animals: Eye and Ear.       Washington, DC: International Life Sciences Institute; 1989: 145-149.
  8. Squire RA, Goodman DG, Valerio MG, Fredrickson T, Strandberg JD, Levitt MH, Lingeman CH, Harshbarger JC. Tumors. In: Benirschke K, Garner FM, Jones TC eds. Pathology of Laboratory Animal. Vol II. Springer-Verlag, New York, 1978: 1070-1071


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