# Secondary Primary Carcinoma Arising on the Flap Skin in the Oral Cavity--Case Series
## 4 Case III  
We present a case of a 76-year-old patient with a 20-year smoking history and no history of alcohol abuse. The patient initially underwent partial maxillectomy for early-stage oral squamous cell carcinoma (OSCC) of the right maxillary gingiva in 1994. Pathohistological analysis revealed pT2 OSCC, and no adjuvant therapy was required. Regular follow-up was maintained for the first 6 years. In 2012, the patient presented with an ulcerated lesion in the region of the previous maxillectomy, infiltrating adjacent cheek soft tissue. The patient experienced difficulty with mouth opening and displayed bloody discharge. A biopsy revealed a new primary OSCC. Multislice computed tomography (MSCT) confirmed spread in the masticatory space and two enlarged lymph nodes at levels I and II on the right side of the neck, staging the disease as cT4 bN2b. A radical maxillectomy was performed, including resection of the masticatory space, segmental resection of the mandibular ramus and infiltrated skin, and a modified radical neck dissection with preservation of the internal jugular vein. Reconstruction of the palate and buccal mucosa was achieved with a regional pectoral muscle flap, while bone was reconstructed using a titanium mesh and the skin with a local corticofacial flap. Pathohistological analysis revealed pT4 aN0 OSCC. Adjuvant radiotherapy was administered (66 Gy/33 fractions). One year later, reconstruction of the maxillary and adjacent soft tissue defect was undertaken due to titanium mesh exposure. Midfacial bone and facial skin were reconstructed with a latissimus dorsi-scapula free flap. Throughout follow-up, the patient was evaluated every 2-3 months for the first 2 years, every 6 months for the next 4 years, and then annually. Each follow-up included a regular physical examination, with an ultrasound of the neck conducted 1-2 times per year and imaging (CT or MRI) of the head, neck, and chest repeated annually. In 2021, the patient presented with new primary synchronous OSCC on the gingiva of the right mandible spreading to adjacent skin (cT4a) and one in the left sublingual region (cT3). The neck was clinically negative. Resection of oral synchronous cancers with segmental mandibular resection and resection of involved skin en bloc with elective left-side selective neck dissection (I-IV) was performed. Bone and oral mucosa defects were reconstructed with an osteocutaneous radial forearm free flap from the patient's left arm, and the involved skin was reconstructed with an axial deltopectoral flap. Pathohistological analysis revealed two synchronous OSCCs: one on the right gingiva (verrucous OSCC, staged pT4a) and one sublingual OSCC (staged pT3). The neck was negative for metastases (N0). Adjuvant radiotherapy was administered (66 Gy/33 fractions). One year later, 29 years after the initial operation, the patient clinically presented with two synchronous overrucous OSCCs arising in the center of the right buccal mucosa (previously reconstructed with a regional flap of the major pectoral muscle) and the center of the sublingual mucosa (previously reconstructed with a radial forearm free flap). The patient underwent the resection of the two oral carcinomas with reconstruction using a rectus abdominis free flap. The histopathological report showed that the material is a part of the tongue, the base of the oral cavity, and the buccal mucosa measuring 9.5 \(\times\) 5 cm; there are two white patches, partly ulcerated, measuring 3 \(\times\) 1.5 \(\times\) 1 cm and 4.2 \(\times\) 2.5 \(\times\) 0.5 cm. Histologically, the tumor is comprised of islands and cords of well-differentiated squamous epithelial cells. It consists of areas of extensive keratinization forming multiple scales and keratin pearls; tumor cells show minimal pleomorphism. Among the described islands and cords, there is an abundant desmoplastic connective stroma permeated with a mononuclear inflammatory infiltrate. No perineural invasion was noted.