Alimentary System

Salivary Gland, Parotid - Basophilic Hypertrophic Focus

Narrative
Comment:
Basophilic hypertrophic foci of the salivary glands have been found only in the parotid gland in mice and rats and usually occur singly (Figure 1 and Figure 2), although multiple foci may be observed (Figure 3, Figure 4, and Figure 5). The foci consist of focal clusters of enlarged acinar cells that contain increased amounts of cytoplasm and, sometimes, enlarged nuclei. The apical cytoplasm is usually vacuolated and pale, while the basilar cytoplasm is deeply basophilic. This change may be seen occasionally in untreated rats, but chemicals, including doxylamine, have produced this change in the parotid gland of F344 rats. This change is not thought to be preneoplastic.
Recommendations:
When a single focus is present, it should be diagnosed as "basophilic hypertrophic focus." Multiple foci should be diagnosed as "basophilic hypertrophic focus, multiple." Severity grading is not necessary, but if an increase in size or number of foci is correlated with chemical exposure, a grading scale should be applied that takes into account both the size and number of foci in each animal.
References:

Botts S, Jokinen M, Gaillard ET, Elwell MR, Mann PC. 1999. Salivary, Harderian, and lacrimal glands. In: Pathology of the Mouse (Maronpot RR, ed). Cache River Press, St Louis, MO, 49-80.

Neuenschwander SB, Elwell MR. 1990. Salivary glands. In: Pathology of the Fischer Rat (Boorman GA, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 31-42.

  • Image of basophilic hypertrophic focus in the parotid salivary gland from a female F344/N rat in a chronic study

    Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study. A focus of hypertrophied cells with increased basophilia is present (arrow).

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<p>Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study. A focus of hypertrophied cells with increased basophilia is present (arrow).</p>

Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study. A focus of hypertrophied cells with increased basophilia is present (arrow).
<p>Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study (higher magnification of Figure 1). A focus of hypertrophied cells with increased basophilia is present (arrow).</p>

Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study (higher magnification of Figure 1). A focus of hypertrophied cells with increased basophilia is present (arrow).
<p>Salivary gland, Parotid - Basophilic hypertrophic focus in a male F344/N rat from a chronic study. Multiple foci of hypertrophied cells with increased basophilia are present (arrows).</p>

Salivary gland, Parotid - Basophilic hypertrophic focus in a male F344/N rat from a chronic study. Multiple foci of hypertrophied cells with increased basophilia are present (arrows).
<p>Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study. Multiple foci of hypertrophied cells with increased basophilia are present (arrows).</p>

Salivary gland, Parotid - Basophilic hypertrophic focus in a female F344/N rat from a chronic study. Multiple foci of hypertrophied cells with increased basophilia are present (arrows).
<p>Salivary gland, Parotid - Basophilic hypertrophic focus in a male F344/N rat from a subchronic study (higher magnification of Figure 4). Multiple foci of hypertrophied cells with increased basophilia are present (arrows).</p>

Salivary gland, Parotid - Basophilic hypertrophic focus in a male F344/N rat from a subchronic study (higher magnification of Figure 4). Multiple foci of hypertrophied cells with increased basophilia are present (arrows).

Authors:

Linda H. Kooistra, DVM, PhD, DACVP
Pathologist
Charles River Laboratories, Inc.
Research Triangle Park, NC

Abraham Nyska, DVM, Diplomate ECVP, Fellow IATP
Expert in Toxicologic Pathology
Visiting Full Professor of Pathology
Sackler School of Medicine, Tel Aviv University Timrat Israel

Reviewers:

Joel R. Leininger, DVM, PhD
Senior Pathologist
MedImmune
Washington, DC

Amy Brix, DVM, PhD, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC