The epidemiology of heritable traits whose prevalence is determined by a balance between mutation and selection is often explored through deterministic models. Here, the properties are explored by simulation of a model population followed through a sequence of closely spaced time points. Mutation and birth and death occur randomly. The condition neurofibromatosis type 1 (NF1) is used as a point of reference. Critical parameters, such as mutation rates and selection forces, are not known precisely for NF1 so speculative values based on published data from Finland and other studies are proposed.

A case of a female child of six years of age with a plexiform neurofibroma of the larynx caused by von Recklinghausen’s disease is presented. Laryngeal involvement in neurofibromatosis type 1 (NF1) is rare and only 19 paediatric cases have been reported. The tumour was biopsied and lateral pharyngotomy with supraglottic hemilaryngectomy was performed in order to relieve obstructive symptoms. Problems related to this unusual tumour localization are discussed and a review of the literature is presented.

Neurofibromatosis is a genetic condition characterized by localized over-growth of mesodermal and ectodermal tissues. Neurofibromatosis type 1 is characterized by cutaneous and skeletal abnormalities. Angiopathy is rare. We describe a new presentation of angiopathy in neurofibromatosis type 1. The patient presented with extensive bruising of the right side of her neck together with intra-oral and pharyngeal submucosal haemorrhage. Radiological investigation confirmed that an aneurysm of the right ascending pharyngeal artery had ruptured. This was successfully embolized without complication.

Neurofibroma affecting the major salivary gland is uncommon. This tumour is particularly rare in the submandibular and sublingual gland.

Here, a case of solitary plexiform neurofibroma of the submandibular gland without any other manifestations of von Recklinghausen's disease is presented. It is probably the first case report of this tumour invading the submandibular gland in a solitary form.