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Feline Lower-Lip Apocrine Sweat Gland Adenocarcinoma with Mandibular Nodal Metastasis: A Case Report
1
24Soom Animal Hospital, 715 Gwonseon-ro, Gwonseon-gu, Suwon 16568, Republic of Korea
2
Department of Veterinary Surgery, College of Veterinary Medicine, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
*
Author to whom correspondence should be addressed.
Vet. Sci. 2026, 13(7), 606; https://doi.org/10.3390/vetsci13070606 (registering DOI)
Submission received: 14 May 2026
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Revised: 18 June 2026
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Accepted: 22 June 2026
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Published: 23 June 2026
(This article belongs to the Special Issue Focus on Tumours in Pet Animals: 3rd Edition)
Simple Summary
Apocrine sweat gland adenocarcinoma is an uncommon feline skin adnexal carcinoma, and lower-lip involvement has been reported infrequently. This report describes a 14-year-old spayed female Siamese cat with lower-lip apocrine sweat gland adenocarcinoma and mandibular lymph node metastasis. Approximately 1 year before diagnosis, the cat had a fluctuant hemorrhagic lesion at the same lower-lip site with a small superficial erosive to ulcerative focus; fine-needle aspiration yielded bloody fluid with cytologically nondiagnostic material. Although the lesion reportedly subsided after empirical treatment, scheduled reassessment and complete clinical resolution were not documented. A firm mass was later identified at the same site, and cytology supported malignant epithelial neoplasia. Histopathology of the excised mass and ipsilateral mandibular lymph node supported a diagnosis of apocrine sweat gland adenocarcinoma with lymphatic invasion and nodal metastasis. The diagnosis was supported by superficial cutaneous location, association with cutaneous adnexal structures, lack of continuity with nearby minor salivary glands, epithelial immunoreactivity, and ancillary histochemical findings. This case illustrates the risk of underestimating a hemorrhagic, superficially eroded lower-lip lesion when cytology is nondiagnostic and objective resolution is not documented. Lower-lip lesions with persistent or subsequent same-site clinical concern may require tissue-based diagnosis and regional lymph node assessment.
Abstract
Apocrine sweat gland adenocarcinoma is an uncommon feline adnexal neoplasm, and lower-lip involvement is rarely documented. A 14-year-old spayed female Siamese cat was evaluated for a firm 1.3 cm right lower-lip mass at a documented hemorrhagic lesion site. Approximately 1 year earlier, the lesion was fluctuant and superficially erosive to ulcerative; fine-needle aspiration yielded bloody fluid with cytologically nondiagnostic material. The lesion reportedly subsided after empirical treatment, but reassessment, tissue diagnosis, and objective confirmation of resolution were not performed. Cytology of the later same-site mass supported malignant epithelial neoplasia. Contrast-enhanced computed tomography (CT) identified a 12.5 × 13.2 × 16.6 mm rim-enhancing mass without mandibular invasion or distant metastasis; the ipsilateral mandibular lymph node was mildly thickened. Histopathology supported a diagnosis of lower-lip apocrine sweat gland adenocarcinoma with lymphovascular tumor emboli, lymphatic invasion, and nodal metastasis. The diagnosis was supported by superficial dermal/subcutaneous location, adjacent adnexal structures, skeletal-muscle separation from nearby minor salivary glands, epithelial immunoreactivity, periodic acid-chiff (PAS) and Alcian blue findings without distinct intratumoral mucin/mucopolysaccharide-rich material. The cat died without necropsy on postoperative day 87. This case supports tissue-based diagnosis and regional lymph node assessment for suspicious feline lower-lip glandular epithelial lesions.
