# “Dry Tap” Fine-Needle Aspiration Biopsy as a Diagnostic Clue in Cyst-like Juvenile Jaw Lesions Mimicking Dentigerous Cysts on Panoramic Radiography and Cone-Beam Computed Tomography

## TL;DR

This paper discusses how dry tap fine-needle aspiration can help distinguish solid odontogenic tumors from cysts in children, even when imaging appears similar.

## Contribution

The paper introduces dry tap as a diagnostic clue for solid juvenile jaw lesions that mimic cysts on imaging.

## Key findings

- Dry tap during biopsy suggests a solid lesion rather than a cyst.
- Imaging alone cannot reliably differentiate true cysts from solid tumors in pediatric patients.
- Two cases showed cyst-like imaging but were confirmed as solid tumors via histopathology.

## Abstract

Pediatric odontogenic tumors are rare but are frequently overlooked because they often mimic simple cysts on routine radiographic examinations. The radiographic appearance on panoramic imaging and cone-beam computed tomography (CBCT) frequently does not correlate with the true biological nature of these lesions. On CBCT, classic odontogenic tumors often demonstrate mixed radiolucent–radiopaque patterns with ill-defined borders, internal calcifications, septations, or other structural features. The diagnostic challenge arises when an odontogenic tumor mimics a unilateral, well-defined radiolucent area or a cystic lesion with clear borders and no associated tooth displacement, erosion, root resorption, or cortical bone dehiscence. Panoramic radiography has inherent diagnostic limitations but remains widely used for routine dental screening. CBCT provides enhanced three-dimensional assessment and improves diagnostic accuracy in the evaluation of jaw lesions. A marked increase in dental follicle diameter necessitates differentiation between cystic transformation, inflammatory processes, and other odontogenic pathologies. Cortical swelling and bone asymmetry warrant careful evaluation. In this context, an atypical cyst-like lesion detected on routine panoramic radiography prompted a needle aspiration biopsy, which revealed a dry tap and suggested a solid lesion. This prompted CBCT evaluation. Two juvenile cases are presented in which clinical findings, panoramic radiography, and CBCT provided discordant diagnostic impressions of cystic-appearing lesions with well-defined borders and bone expansion. These cases illustrate a diagnostic pathway in which imaging demonstrates a cyst-like appearance with benign radiological features, fine-needle aspiration biopsy reveals the absence of cystic fluid, and histopathology confirms that radiology alone cannot reliably distinguish true cysts from solid odontogenic tumors in pediatric patients.