Pathology of the Head and Neck

238 L. Michaels8.2.1.4 Relapsing Polychondritis8Relapsing polychondritis is a rare disease of unknownaetiology characterised by recurring bouts of inflammationaffecting cartilaginous structures and the eye.Although the cartilage of the external ear is most frequentlyinvolved and that of the nose next in frequency,it is the inflammation with destruction of the cartilagesof the respiratory tract, particularly those of the larynx,which threatens life, and in most cases where death hasresulted from the condition it is from respiratory obstructiondue to such cartilage damage.The cartilage of the pinna, is recurrently acutely inflamedand this leads eventually to a cobblestone appearanceresembling boxer’s ear. Inflammation of thenasal septum leads to a sinking of this structure, producinga “saddle nose” appearance. Involvement of laryngealand tracheal cartilages may lead to respiratorydifficulty. Rib cartilages may be swollen and tender.Episcleritis or scleritis, iritis, conjunctivitis or keratitismay also be found in relapsing polychondritis. Heart lesionsare characteristically aortic, showing signs of regurgitation.The histology of this affliction is dealt within Chap. 7.8.2.1.5 GoutGout is manifested both as an acute arthritis that is relatedto deposits of urates in the joint capsule, most frequentlyin the big toe joint, and as tophi in non-articulartissues. The external ear is one of the most frequentplaces for the latter and deposits may occur in the helixand antihelix. They may ulcerate, discharging a creamywhite material within which needle-like crystals of sodiumurate may be detected on microscopy. For histology,see Chap. 7.8.2.1.6 OchronosisOchronosis (alkaptonuria) is an inherited disease of themetabolism in which a step in tyrosine metabolism isdisturbed, resulting in accumulation of homogentisicacid in a variety of places, but especially in the cartilages.The substance is colourless in the urine whenfirst passed, but darkens to a black or brown polymeron standing. The disease is inherited as an autosomalrecessive.In the external ear there may be one or both of twomanifestations: (a) dark colour of the wax; when seenin a child this may be the first manifestation of ochronosis;(b) dark colour of the aural cartilage due to thebinding of the homogentisic acid to the cartilage groundsubstance.Fig. 8.2. Idiopathic pseudocystic chondromalacia of the cartilageof the auricle. Note the cystic cavity in the cartilage lined with degeneratedcartilage that has lost its elastic tissue. Normal elastictissue is present further away from the pseudocyst at the left handcorner. Reproduced from Michaels and Hellquist [68]8.2.2 Pseudocysticand Cystic Lesions8.2.2.1 Idiopathic PseudocysticChondromalaciaIdiopathic pseudocystic chondromalacia occurs mainlyin young and middle-aged adults. The gross appearanceis one of a localised swelling of the auricular cartilage. Acut surface shows a well-defined cavity in the cartilage,which is distended with yellowish watery fluid [42]. Microscopically,the cavity shows a lining of degeneratedcartilage on one surface (Fig. 8.2); on the other surfacethe cartilage is normal. It seems possible that the fluid isan exudate from undamaged perichondrial vessels thatcannot be absorbed by the damaged perichondrial vessels.The association of this lesion with severe atopic eczemain four children [27] suggested that minor traumafrom repeated rubbing of the auricle may play a part.Small pseudocysts of the elastic cartilage of the pinnamay also be seen in the vicinity of inflammatory or neoplasticlesions of that region.8.2.2.2 First Branchial Cleft CystA developmental origin from the first branchial cleft hasbeen assumed in some fistulas, sinuses, and cysts arisingin the periauricular and the parotid region and also insome fistulas arising in the neck that are located abovea horizontal plane passing through the hyoid bone. Thecommonest of these lesions is the preauricular sinus.This usually shows a stratified squamous epithelial lining,but occasionally it may be of respiratory epithelium,