Henrik B. Hellquist MD, PhD, SAPath(Stockh), FCAP’s research while affiliated with Haukeland University Hospital and other places

The ear is not a single organ, but two, being the peripheral receptor site both for stimuli derived from sound waves and for changes of posture. The structures subserving both of those functions are developed from an invagination of ectoderm early in embryonic life — the otocyst — to produce the epithelia of the membranous labyrinth of the inner ear. Superimposed upon, and developing slightly later, the first and second branchial arch systems provide structures which augment the hearing function. The endodermal component of the first branchial system, the branchial pouch, gives rise to the Eustachian tube and middle ear epithelia and the corresponding ectodermal outgrowth, the first branchial cleft, to the external ear epithelia. The connective tissue part of the local branchial system, the first and second branchial arches, produces the ossicles. The eighth cranial nerve outflow from the central nervous system grows to link up with the sensory epithelia lining the otocyst-derived cochlear and vestibular labyrinths and the cartilaginous, bony and muscular conformations of the ear are developed from the mesenchyme surrounding these early epithelia.

The temporal bone is affected in the majority of fractures of the base of the skull. Although such lesions are frequent at autopsy, there has hardly been any study of fractures of the temporal bone in pathological material and what knowledge there is has largely been derived from clinical and radiological observations.

The development of the inner structure of the nose and paranasal sinuses is initiated by the formation in the second month of an ectodermal thickening, the olfactory placode, on each side. These are each placed above and medial to a maxillary swelling, which has been formed above a mandibular swelling, the four swellings, two maxillary and two mandibular (the latter of which soon fuse to form the lower jaw) being arranged around a primordial mouth cleft. Medial to each olfactory placode a swelling is formed, the medial nasal fold. The fusion of the two medial nasal folds gives rise to the frontonasal process, a precursor of the external nose and nasal septum. Lateral to each olfactory placode, a lateral nasal process on each side forms the groove between the nose and the eye. The groove between the maxillary process and the lateral nasal fold on each side gives rise to the nasolacrimal duct. The olfactory placode forms a pit, which sinks deeper and eventually joins posteriorly with the oral cavity. The pit of the nasal cavity produces ledges on its lateral wall, which are each eventually supported by a bony skeleton to produce the turbinates. Paranasal sinuses bud off the main nasal cavity (Fig. 12.1).

Pagef’s disease (osteitis deformans) is a common condition affecting particularly the skull, pelvis, vertebral column and femur in people over 40 years of age. The cause is not yet certain, but the presence in many cases of paramyxovirus-like structures seen within osteoclasts has prompted the suggestion that Pagefs disease may be of viral aetiology and the measles virus and canine distemper viruses have been under scrutiny as candidates. The pathological change is one of active bone formation proceeding alongside active bone destruction. The affected bones are enlarged, porous and deformed. Microscopically, bone formation is seen in trabeculae of bone with a lining of numerous osteoblasts. A mosaic appearance is formed by the frequent successive deposition of bone, cessation of deposition resulting in thin, blue “cement lines”, followed again by resumption of deposition and its cessation, and so production of further cement lines. Bone destruction is shown by the presence of numerous, large osteoclastic giant cells with Howship’s lacunae. Areas of chronic inflammatory exudate intermixed with the bone are common (Fig. 10.1).

It is doubtful whether a lesion composed entirely of adult fibrous tissue with collagen and sparse fibrocytes is ever neoplastic; it is usually the endresult of an inflammatory process. Occasionally a fibroblastic form of meningioma may be so poorly cellular as to resemble a fibrous tumour. In such cases the concentrically laminated arrangement of the fibrous tissue may be the only diagnostic feature of meningioma (see Chapter 18). Post-inflammatory fibrous tissue in the nose likewise may present such an arrangement, so it is necessary to search a wider area of the lesion for the presence of more diagnostic cellular whorls of meningioma.

The external ear is a specialised appendage of the skin, so that its neoplasms are most frequently those derived from skin. Bony neoplasms also occur, as would be expected from the presence of bone nearby, but the cartilage of the ear seems to have no neoplastic propensity. The following account will deal only with those tumours that have a predilection for that region and those that pose special diagnostic histological and clinical problems.

In the vestibule and nostril, papillomas are usually stratified squamous arising on the skin surface. Rarely do they recur after simple removal, and malignant transformation is seldom a problem. Abnormal hyperplastic changes of the epithelium are frequent, but if similar criteria of assessment for possible cancerous or precancerous change are used to those applied in other stratified squamous epithelia (see Chapter 34), a diagnosis of malignancy will be unusual.

Squamous cell papillomas are frequent in the larynx of adults. They also found in children where, because of the much narrower diameter of the airway, the more widespread involvement in the larynx and the greater tendency to recurrence, the symptoms are more serious, and treatment is more urgent and difficult. It is thus customary to divide the condition on the basis of the age of the patient into juvenile and adult types. In some juvenile cases the papillomas persist into adult life. The pathological changes are similar at all ages, and will be described first before a discussion of the natural history of the lesion.

The basic outlines of development of the larynx are clear and uncontroversial. It is accepted that the epithelium of the larynx arises from the upper end of an outgrowth from the endoderm of the ventral wall of the pharynx. In growing caudally this outgrowth eventually produces the trachea, and bifurcates to produce the bronchi and lungs.

Squamous cell carcinoma, although rare, is the commonest malignant neoplasm of the nasal vestibule, which is a region covered by modified hair-bearing skin. The other two important malignant neoplasms of the skin, malignant melanoma and basal cell carcinoma, also occur here, but with less frequency.