Delayed diagnosis of palatal adenoid cystic carcinoma: Review of diagnostic workup and image features of perineural spread.

Objectives: Adenoid cystic carcinoma (ACC) is the malignancy most likely to spread perineurally. Delayed diagnosis often leads to undetected perineural spread (PNS). Better understanding of diagnostic processes, clinical and imaging features in ACC may allow earlier diagnoses.

Materials And Methods: A retrospective records search of the University of Washington Radiology archive identified patients with palatal ACC diagnosis and pre-treatment MDCT and/or MRI. Demographic data, clinical findings, diagnostic workup history and image features including the presence of PNS were recorded.

Results: 44 patients met inclusion and exclusion criteria. Symptoms included pain, mass, numbness, and sinonasal congestion. The most common finding on clinical examination was visible or palpable palatal mass. 55% of patients were evaluated by a dentist pre-diagnosis. Most common initial impressions were infection and/or dental disease. PNS was identified in 81.8% of patients, most commonly at pterygopalatine fossa, palatine foramina/canals, Vidian canal, or foramen rotundum. PNS was statistically significantly associated with paresthesia (p = 0.003) but not with tumor size, age, gender, or tobacco history. 44% of patients were diagnosed ≥1 year from initial symptoms, with a mean delay of 18.3 (range < 1-72) months.

Conclusions: This study represents the first analysis of the nature of the diagnostic process of palatal ACC. Majorities of patients were evaluated by a general dentist pre-diagnosis. PNS was identified in a majority of patients and all the patients who presented with paresthesia had evidence of PNS. Despite patients presenting with paresthesia, palatal ACC is often initially misdiagnosed resulting in delayed diagnosis.