Immunohistochemical Expression of Involucrin in a Multirecurrent Canine Cutaneous Squamous Cell Carcinoma (SCC) Nongnut Assawawongkasem1*and Achariya Sailasuta2 12nd year Ph.D. Student Pathobiology program, 2Companion Animal Cancer Research Unit, CAC-RU, Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University. Bangkok. 10330. *Corresponding author; email: gee32vet@gmail.com Materials & Methods SCC were collected from a 7 years, white color, male dog with 4 times surgical treatment, a 2-3 cm in diameter at inguinal area, during 8 months observation, The mass was presented after chronic licking (>8 mths) at the healing castrated area. Subsequently, the clinical signs and treatments were shown in Table 1. The tumor biopsies were collected Introduction & Objective From the record during 2010-2013, the skin tumors in dogs comprised 31.5% of all the diagnosed tumor cases and 22.5% of them is SCC and many of SCC cases were multi-recurrence and more progressive within 2-3 months after treatments. Involucrin, a cornified envelope protein, have been widely used as a marker of early stage of human terminal keratinocyte differentiation. It had been studied more in human dermatology and medical research about normal epidermal renewal structures, patterns and functions, including various immune disease and genetic defect of skin lesion. Nowadays, INV is an interesting candidate to be tumor marker of human SCC as diagnosis and prognosis purpose of premalignant lesion of keratinocytes. However, the use of INV for cancer prognosis in veterinary has been limited. Therefore, we have started many researches on the expression of INV. The previous studies shown that INV demonstrated positive in dog skin, and similar staining patterns among various anatomic sites, breeds. Moreover, increasing of INV expression has been used for parallel analysis for canine atopic dermatitis. On the contrary, the decreasing of INV in most canine skin tumor, poor- differentiate SCC respectively. The objectives of this study are revealed to demonstrate the Immunohistochemical (IHC) expression of Involucrin (INV) and histopathological grading in a multirecurrence canine cutaneous SCC case. for histopathological classified (1) and the INV-IHC staining was performed as previous described (2) Results and Conclusion The results of the 2nd and 4th times of recurrence cutaneous SCC, the 4th time revealed progressive undifferentiated SCC and decreased of INV-IHC expression in comparison to the 2nd time. In addition, that relate to the short period of recurrence. However, no remarkable evident of metastasis was recognized. It is also speculated that INV-IHC expression should be a potential candidate marker which might be developed and exploited for canine SCC diagnosis, prognosis and therapeutic planning in the Clinical case. Figure 1. Characteristic changed in recurrence mass at 2 times (a, b) and 4 times (c, d) of excisional biopsy c d a b Table 1. Clinical information Day 0 1st Local excision surgery in 3 month ago Alert, normal appetite Skin mass 2x3 cm w fistula tract No lymph node enlargements Blood profile in reference intervals +Staphylococcus in lesion FNA:SCC Carboplatin 7 ml + NSS 20 ml slow IV CPM 0.4 IM RX 3wk : Firocoxib (57)1/2 SID pc Fish oil (500) 1 SID ac VitaminA 1 BID pc Baytril (50) 1 SID pc mucopuricin ointment Week 3 Skin mass less exudates and redness Biopsy (removed mass): SCC Local excision surgery (2)  not complete remove invaded muscle Daily dressing complete healing Repeat Rx 2 week as like as previous Week 6 Recurrent mass 1x1x0.5 cm FNA: SCC Blood profile: normal RX 2wk : Firocoxib (57)3/4 SID pc Doxycyclin (100) 1 SID pc   Week 8 Local excision surgery (3) Week 12 Recurrence mass 1x1.5x1 cm FNA: epidermal inclusion cyst, Lt inguinal lymph node active X-ray: no bone involved and metastasis Week 16 Recurrent mass and invade to proximal-caudal of Lt hind limb Local excision surgery (4) Daily dressing infected wound and rupture in day 5 References Goldschmidt MH and Hendrick MJ 2002. Tumors of the skin and soft tissues. In: Tumors in domestic animals. 4th ed. DJ Mueten (ed). Ames: Iowa State Press: 45-117. Sailasuta A, Suriyaphol G, Theerawatanasirikul S and Assawawongkasem N. 2013. Involucrin mRNA expression in formalin – fixed paraffin embedded tissues of canine epidermal squamous cell carcinoma. Proceeding 38th International Conference on Veterinary Science, Muangthong Thani, Thailand, January 16-18: 10.