Primary intraosseous squamous cell carcinoma in a dentigerous cyst.

Dear Editor,

A 76-year-old male complained of a swelling in relation to the right mandibular molar for 4 months. Intraorally, a fluctuant swelling was present on the alveolar ridge measuring 4 cm × 3 cm. Orthopantomogram revealed an impacted 48 with soft tissue shadow. Computed tomography scan revealed a pericoronal cystic lesion with expansion of the buccal and lingual cortices [Figures 1 and 2]. The case was provisionally diagnosed as dentigerous cyst. On excisional biopsy, the gross specimen exhibited a cystic structure surrounding the tooth at the cementoenamel junction [Figure 3]. Histopathology exhibited hyperplastic cystic lining epithelium with connective tissue wall. The epithelium is of stratified squamous type, exhibiting irregular rete processes, nuclear hyperchromatism, pleomorphism and increased mitosis. Tumor cells are seen arising from the lining epithelium and extending into the lumen [Figures 4 and 5]. Connective tissue wall is infiltrated with tumor cells in some areas. Mucicarmine and periodic acid–Schiff stain was negative. Lining epithelium resembling reduced enamel epithelium was present in a section. A diagnosis of squamous cell carcinoma (SCC) arising from dentigerous cyst was made.

Figure 1

Orthopantomogram demonstrating impacted 48 and soft tissue shadow

Figure 2

Computed tomography scan demonstrating bicortical expansion with buccal perforation

Figure 3

Gross specimen of the lesion

Figure 4

Photomicrograph showing folded hyperplastic cystic lining epithelium of stratified squamous type exhibiting dysplastic features. (H and E stain, ×10)

Figure 5

Photomicrograph showing tumor cells with hyperchromatism, pleomorphism, altered nuclear cytoplasmic ratio and keratin formation. (H and E stain, ×40)

The patient was later referred to an Oncology center. Associating the histopathological and imaging features[12] a diagnosis of primary intraosseous SCC (PIOSCC) was made.

PIOSCC is defined as a “SCC arising within the jaw, having no initial connection with the oral mucosa and presumably developing from residual odontogenic epithelium or an odontogenic cyst or tumor.”[2] Incidence of malignant transformation from odontogenic cysts ranges from 0.13% to 2%.[3] PIOSCC arising from odontogenic cysts other than keratocystic odontogenic tumor commonly occurs in mandible[4] with male predilection, at an average age of 56 years.[4] Radiation and chemotherapy are included in the treatment modalities. The 5-year survival rate of PIOSCC varies between 30% and 40%.[5]

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