Classification system that describes anomalies seen in the first branchial cleft. Type 1 – general anatomic course locates in a horizontal direction with tract running superior to the facial nerve trunk, along the external auditory canal; represents duplication anomaly of ectodermal layer with involvement culminating in a closed sac adjacent to midportion of the middle ear. Type 2- anomaly is of both cartilage and membranes of external auditory canal arising from both first cleft and first and second branchial arches; antomically usually involves parotid gland and lies vertically over the facial nerve, with sinus opening of blind sac (if present) opening inferior and posterior to mandibular ramus.