Special Senses System

Zymbal's Gland - Hyperplasia

Narrative
Comment:
Zymbal's gland hyperplasia (Figure 1, Figure 2, Figure 3, and Figure 4) is generally a focal change. Hyperplasia can occur in the compact Zymbal’s gland (Figure 1 and Figure 2) or in the diffuse Zymbal's gland-type sebaceous tissue in the lamina propria of the external ear canal (Figure 3 and Figure 4).

Hyperplastic areas in the Zymbal's gland are characterized by a focal increase in the number and often the size of the sebaceous acini, often with slight distortion of the lobular architecture and slight compression of the adjacent tissue. They are composed of variably sized acini lined by relatively well-differentiated epithelial cells with enlarged nuclei and cytoplasm that is more basophilic and less foamy than in normal cells. The normal maturation sequence of the acinar cells may be obscured or absent. Hyperplasia lacks the pronounced cellular atypia, marked architectural distortion, and invasion of adjacent tissue, which are features of neoplastic lesions. Hyperplasia may be a reactive change secondary to inflammation or degeneration. Hyperplasia occurring in the absence of concurrent degeneration or inflammation is considered a preneoplastic lesion and an early-stage change in the morphologic continuum from hyperplasia to carcinoma.
Recommendations:
If considered a primary change, Zymbal's gland hyperplasia should be diagnosed and assigned a severity grade. When secondary to inflammation or degeneration, Zymbal's gland hyperplasia should not be diagnosed separately (unless warranted by severity), but should be described in the pathology narrative.
References:

Copeland-Haines D, Eustis SL. 1990. Specialized sebaceous glands. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 279-294.

Abstract: https://www.ncbi.nlm.nih.gov/nlmcatalog/9002563

Hebel R, Stromberg MW. 1986. Sensory organs. In: Anatomy and Embryology of the Laboratory Rat, 2nd ed. BioMed Verlag, Wörthsee, Germany, 218-224.

Huff JE, Eastin W, Roycroft J, Eustis SL, Haseman JK. 1988. Carcinogenesis studies of benzene, methyl benzene, and dimethylbenzenes. Ann NY Acad Sci 534:427-440.

Abstract: http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1988.tb30132.x/abstract

Laws JO, Rudali G, Royer R, Mabile P. 1955. The early changes produced in the auditory sebaceous gland (Zymbal’s gland) of the rat by 2-acetylaminofluorene. Cancer Res 15:139-143.

Abstract: http://cancerres.aacrjournals.org/content/15/3/139

National Toxicology Program. 1990. NTP TR-372. Toxicology and Carcinogenesis Studies of 3,3'-Dimethoxybenzidine Dihydrochloride (CAS No. 20325-40-0) in F344/N Rats (Drinking Water Studies). NTP, Research Triangle Park, NC.

Abstract: https://ntp.niehs.nih.gov/go/8884

National Toxicology Program. 1993. NTP TR-400. Toxicology and Carcinogenesis Studies of 2,3-Dibromo-1-Propanol (CAS No. 96-13-9) in F344/N Rats and B6C3F1 Mice (Dermal Studies). NTP, Research Triangle Park, NC.

Abstract: https://ntp.niehs.nih.gov/go/12251
  • Image of hyperplasia in the Zymbal's gland from a female F344/N rat in a chronic study
    Zymbal's gland - Hyperplasia in a female F344/N rat from a chronic study. There is a focal increase in the number of sebaceous acini (arrow) with slight lobular architectural distortion around a dilated duct.
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Zymbal's gland - Hyperplasia in a female F344/N rat from a chronic study. There is a focal increase in the number of sebaceous acini (arrow) with slight lobular architectural distortion around a dilated duct., basic_html
Zymbal's gland - Hyperplasia in a female F344/N rat from a chronic study. There is a focal increase in the number of sebaceous acini (arrow) with slight lobular architectural distortion around a dilated duct., basic_html
Zymbal's gland - Hyperplasia in a female F344/N rat from a chronic study (higher magnification of Figure 1). Hyperplasia is characterized by a focal increase in the number of sebaceous acini and slight lobular architectural distortion., basic_html
Zymbal's gland - Hyperplasia in a female F344/N rat from a chronic study (higher magnification of Figure 1). Hyperplasia is characterized by a focal increase in the number of sebaceous acini and slight lobular architectural distortion., basic_html
Zymbal's gland - Hyperplasia in a male Fischer 344/N rat from a chronic study. There is an increase in the number of sebaceous acini with slight lobular architectural distortion and compression of adjacent tissue (arrow in the diffuse Zymbal's gland tissue in the external ear canal., basic_html
Zymbal's gland - Hyperplasia in a male Fischer 344/N rat from a chronic study. There is an increase in the number of sebaceous acini with slight lobular architectural distortion and compression of adjacent tissue (arrow in the diffuse Zymbal's gland tissue in the external ear canal., basic_html
Zymbal's gland - Hyperplasia in a male Fischer 344/N rat from a chronic study (higher magnification of Figure 3). Hyperplasia (arrow) is characterized by a focal increase in the number of sebaceous acini with slight lobular architectural distortion and compression of adjacent tissue in the diffuse Zymbal's gland tissue, is present in the external ear canal., basic_html
Zymbal's gland - Hyperplasia in a male Fischer 344/N rat from a chronic study (higher magnification of Figure 3). Hyperplasia (arrow) is characterized by a focal increase in the number of sebaceous acini with slight lobular architectural distortion and compression of adjacent tissue in the diffuse Zymbal's gland tissue, is present in the external ear canal., basic_html

Author

Margarita M. Gruebbel, DVM, PhD, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Reviewers

Ruth E. Hurley, DVM, PHD, DACVP
Senior Veterinary Pathologist
Huntingdon Life Sciences
North Brunswick, NJ

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC