Lipomatosis of the parotid salivary gland: 2 case reports and review of the literature on fat-containing salivary gland lesions

Peer review under responsibility of Faculty of Veterinary Medicine, Cairo University.

Figures & data

ig. 1 A: Photograph of case 1 showing a well-defined soft tissue mass on the right parotid region. B: Photograph of case 2 showing a right retromandibular soft tissue mass.

ig. 2 A: Microphotograph of excised tissue from case 1 showing an admixture of mature adipocytes interspersed with well-differentiated salivary acini and few salivary ducts. Haematoxylin and eosin stain, 4×. B: Microphotograph of excised tissue from case 2 showing a similar admixture of adipocytes and well-differentiated salivary acini. Haematoxylin and eosin stain, 4×.

ig. 3 A: Radiographic image of the head of the case 2 showing a soft tissue opacity on the right parotid region and no evidence of osteolyis. B: Transverse plan image of computerized tomography from the head of the case 2 showing a multi-lobulated infiltrative mass occupying the right parotid gland. No evidence of osteolysis was present. The right mandibulary gland had an heterogenous appearance but histology showed normal salivary gland tissue. On the left side, just ventral to the left mandibulary salivary gland there was a soft tissue opacity structure with air-filled, of unknown significance, that had cytological features of inflammation and disappeared with an antibiotic course.

able 1 Description of the cases of fat-containing salivary gland lesions found on a literature review, including original diagnoses and proposed diagnoses in the authors’ opinion.

Case	Author	Age	Sex	Breed	Salivary gland affected	Duration of swelling/clinical signs	Size	Treatment	Follow up	Histological findings	Original diagnosis	Diagnosis in authors opinion
1	Bindseil et al. [14]	11	M	Beagle	Mandibulary (side unknown)	1 year	7 × 6 × 5 cm	Gland excision	NS	Salivary gland with a marked fatty infiltration separating the individual glands into groups of various sizes sparing the piece that appeared grossly normal.	Salivary gland lipomatosis	Salivary lipomatosis
2	Brown et al. [13]	5	F	Labrador	Left parotid	Slow growing mass	2.5 × 1.5 × 1 cm	Gland excision	NS	Extensive replacement of parenchymal tissue by irregular lobules of uniform, well-differentiated fat cells. Portions of persisting glandular tissue had the typical histological appearance of salivary gland. None of the tissues appeared to have a distinct capsule defining the margins of the gland or the fatty tissue within the gland.	Lipomatous infiltration of salivary glands	Salivary lipomatosis
3	Brown et al. [13]	8	F	Retriever	Parotid (side unknown)	Slow growing over 4 months	7 × 5 × 3 cm	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
4	Brown et al. [13]	10	FN	Schnauzer	Right Parotid	Firm swelling increasing in size	5 × 4 × 2 cm	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
5	Brown et al. [13]	n/a	FN	ESS	Right submandibular	Slow growing mass	Twice normal	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
6	Brown et al. [13]	7	M	Crossbreed	Left submandibular	Mass more than 4 weeks duration	2 cm	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
7	Brown et al. [13]	14	M	Terrier crossbreed	Right submandibular	Dysphagia	2 × 1 cm	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
8	Brown et al. [13]	4	F	Golden retriever	Submandibular (side unknown)	Salivary gland swelling	1.5 cm	Gland excision	NS		Lipomatous infiltration of salivary glands	Salivary lipomatosis
9	Spangler and Culbertson [6]	NS	M	NS	NS	NS	NS	NS	NS	NS	Fatty infiltration/degeneration	Uncertain
10	Spangler and Culbertson [6]	NS	M	NS	NS	NS	NS	NS	NS	NS	Fatty infiltration/degeneration	Uncertain
11	Spangler and Culbertson [6]	NS	NS	NS	NS	NS	NS	NS	NS	NS	Fatty infiltration/degeneration	Uncertain
12	Kitshoff et al. [4]	6	F	Boerboel	Parotid (side unknown)	Growing over 18 months	10 × 5 × 5 cm	No treatment	Continued growing- in 14 months has grown 30%	Multifocal to coalescing single or clusters of blood-filled vessels lined by flattened endothelial cells with narrow, elongated, basophilic nuclei. These regions were embedded in adipose tissue with multifocal areas of intervascular remnants of differentiated serous salivary gland tissue with multifocal small ducts.	Infiltrative angiolipoma	Angiolipoma
13	Clark et al. [8]	10	FN	Golden Retriever	Minor salivary gland close to right tonsillary fossa (side unknown)		5 × 6 cm (mass) plus 1.5 × 0.5 cm pedicle	Mass excision	No regrowth after 6 months	Lobules of mature adipose tissue with smaller amounts of salivary tissue and ducts, surrounded by a fibrous connective tissue capsule	Sialolipoma	Sialolipoma
14	Rodinõ Tilve et al. [7]	8	MN	Boxer	Right parotid	Three weeks	NS	Gland excision	No recurrence after 7 months	Presence of mature adipocytes admixed with foci of salivary tissue composed of both ductular and acinar elements The mass was partially surrounded by a fibrous capsule and there was normal salivary gland and a linear area of fibroplasia admixed with neovascularisation	Sialolipoma	Sialolipoma
15	Rodinõ Tilve et al. [7]	9	FN	Lurcher	Right parotid	4 weeks	NS	Excision	No recurrence after 16 months	Multilobular, encapsulated neoplastic mass composed of approximately 60% adipose tissue that entrapped normal-appearing salivary tissue with a scant to moderate fibrovascular supporting stroma. Normal ducts were present within islands of salivary tissue with occasional abnormal ducts lined by large epithelial cells with voluminous, eosinophilic cytoplasm (oncocytic metaplasia) Frequently abnormal ducts were dilated with occasional intraductal mineralised material and surrounded by mild lymphocytic inflammation. The mass was surrounded by a thin, fibrous capsule that bordered adjacent non-neoplastic connective and adipose tissue.	Sialolipoma	Sialolipoma

NS – NOT SPECIFIED.