Wilcox et al (2019) reported on 193 dogs with squamous cell carcinoma.
Dermal only – not nail or elsewhere
54% were in predisposed areas, 46% were in nonpredisposed areas – periarticular, ventral neck, perianal.
White coat – 56%
5 dogs were hypercalcemic
39% had actinic change, 47% had no actinic change,
60% invasive, 11% noninvasive
13% had lymphovascular invasion
3 cases had papillomavirus evidence
22% metastasis 15% at presentation (Lymph node 9% and lung 6%) 7% developed mets later – Ln, Lung and 3 dogs elsewhere.Cunha et al (2023) reported on 54 cases and metastasis was in 34%.
Dos Santos et al (2023) reported on metastasis in 12 of 309 cases (4%). Most were on the abdomen.
Willcox JL, Marks SL, Ueda Y, Skorupski KA. Clinical features and outcome of dermal squamous cell carcinoma in 193 dogs (1987-2017). Vet Comp Oncol. 2019 Jun;17(2):130-138.
Dos Santos A, Lamego ÉC, Eisenhardt LM, et al. Prevalence and anatomopathological characterization of cutaneous squamous cell carcinomas with regional and distant metastases in dogs and cats: 20 cases (1985-2020). Vet Comp Oncol. 2023; 21: 291-301.
Weiner (2021) wrote a review of the follicular tumors in dogs. This review provides and excellent overview of the hair follicle and tumors that develop in dogs.
Sabattini et al () reported on those sebaceous tumors with reserve cells >50% of population. These would include sebaceous epithelioma and carcinoma.
30 cases
Peripheral invasion 9 cases
5 cases intravascular invasion
3 systemic metastasis all had peripheral invasion, intravascular emboli and MI >50Bettini et al (2009) reported on one dog with a sebaceous epithelioma and metastasis to lymph node and lung.
Bettini G, Morini M, Mandrioli L, Capitani O, Gandini G. CNS and lung metastasis of sebaceous epithelioma in a dog. Vet Dermatol. 2009 Aug;20(4):289-94. doi: 10.1111/j.1365-3164.2009.00762.x.
Sabattini S, Bassi P, Bettini G. Histopathological Findings and Proliferative Activity of Canine Sebaceous Gland Tumours with a Predominant Reserve Cell Population. J Comp Path 152: 145-152.
Apocrine sweat gland carcinomas
Immunohistochemically, the tumor cells were intensely positive for cytokeratin 7 and 20 and negative for S100 protein.
In the normal skin, co-expression of CK8/18 was found in the glandular epithelium of apocrine sweat glands, and single CK8-immunoreactivity was detected occasionally in the external root sheath at the isthmus and suprabulbar regions of the hair follicles. Sebaceous glands negativeCanine
Simko E, Wilcock BP, Yager JA. A retrospective study of 44 canine apocrine sweat gland adenocarcinomas. Can Vet J. 2003;44:38-42.
44 cases
followup on 25
5 of 44 invaded vessels
1 of 25 metastasized
Schulman, Lipscomb, Aitkin JVDI 17: 403-411
26 dogs
clear cell morphology
DDX balloon melanoma, sebaceous carcinoma
PAS positive
Oil red o negative
Cytokeratin + (29 of 29)
Vimentin + (29 of 29)
S100 + (24 of 29)
Melan A + (8 of 12)
SMA –
Some have cartilage
22 had some follicular differentiation
3 had metsIn a case reported by Sakuma et al (2010) neoplastic cells were positive for pan-cytokeratin (CK) (AE1/AE3 and CAM5.2), CK8 and CK18, but negative for pan-CK (KL1), CK7, CK14, CK16 and CK20. They are also double positive vimentin and cytokeratin.
Sakuma A, Nishiyama S, Yasuno K, Ohmuro T, Kamiie J, Shirota K. A case of canine cutaneous clear cell adnexal carcinoma with prominent expression of smooth muscle actin. J Toxicol Pathol. 2010; 23: 265-269.
Schulman FY, Lipscomb TP, Atkin TJ. Canine cutaneous clear cell adnexal carcinoma: histopathology, immunohistochemistry, and biologic behavior of 26 cases. J Vet Diagn Invest. 2005; 17: 403-411.
Yasuno K, Nishiyama S, Suetsugu F, Ogihara K, Madarake H, Shirota K. Cutaneous clear cell adnexal carcinoma in a dog: special reference to cytokeratin expression. J Vet Med Sci. 2009; 71: 1513-1517.
This is a synomym for clear cell adnexal carcinoma
Mikaelian and Wong reported 30 cases. All cases were PAS positive for glycogen, and the cells are CK (AE1/AE3) + and vimentin + in 29
4 of 8 had metastases to the local lymph nodesMikaelian I, Wong V. "Follicular stem cell carcinoma: histologic, immunohistochemical, ultrastructural, and clinical characterization in 30 days". Vet Pathol. 2004; 41: 302.
eccrine syringofibroadenoma.