Objective: To report two cases of solid type primary intraosseous carcinoma (PIOC) with a critical appraisal of one of the WHO diagnostic criteria. Summary: Both patients had radiographic and histopathologic findings showing massive mandibular destruction as well as the involvement of the inferior alveolar nerve, without lip or chin paresthesia. Patients were treated through hemimandibulectomy followed by reconstruction through fibula free flap and forearm flap. Conclusion: Lip and/ or chin paresthesia are rather frequent in metastatic and salivary gland tumors but not in primary tumors of the jaws. Reasons for such a discrepancy are mostly unknown. A few hypotheses are put forward here. It is the opinion of the authors that most of the diagnostic criteria for solid type PIOC are acceptable. However, the criterion "absence of ulcer formation on the overlying mucosa" mainly depends on the dimension of the tumor at diagnosis. Keywords: diagnostic criteria, oral surgery, paresthesia, primary intraosseous carcinoma