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Aims: Primary localised pleural neoplasms are a rare group of thoracic tumours, with solitary fibrous tumour representing the most frequently encountered entity. Two cases of localised pleural neurofibromas involving the pleura are described., Methods and Results: The patients were both female: 78 and 29 years of age. In the former a pleural-based lesion was identified on a chest radiograph after she presented with shoulder pain. The second patient was known to have neurofibromatosis type I, and the pleural lesion was found incidentally during excision of a metastatic malignant peripheral nerve sheath tumour of the lung. Both tumours were localised and composed histologically of bland neoplastic spindle cells embedded in a loose collagenous matrix. There was variable immunoreactivity for S100 and CD34, while ultrastructure examination in the two cases showed a mixture of nerve sheath cell types., Conclusion: To the best of the authors' knowledge, localised neurofibromas have not been previously reported within the pleura. The presence of a bland spindle cell pleural neoplasm immunoreactive for CD34 may potentially be mistaken for a solitary fibrous tumour. While distinction is usually achieved on close attention to the histological features, staining with S100 protein, especially in small biopsies, should be considered to exclude a neurofibroma.

A 76 year old white woman presented with a four month history of dysphagia and weight loss. Clinical, radiological, and endoscopic examination revealed a pigmented mass in the lower third of the oesophagus. The preoperative diagnosis, including biopsy examination, was that of malignant melanoma. Following oesophageal resection, the mass was found to be a localised, relatively superficial tumour with light, electron microscopic, and immunohistochemical features common to both Schwann cells and melanocytes. The patient survived 46 months after surgery and died of a stroke, with no evidence of tumour recurrence. The tumour is presented as a case of melanocytic schwannoma, with unique features when compared with oesophageal melanotic schwannomas and malignant melanomas described in the literature. The differential diagnosis is discussed and an origin from a common precursor cell of neural crest origin is postulated.

Thyroid tissue from 18 consecutive cases of Hashimoto's thyroiditis treated surgically were stained immunohistochemically for neurone specific enolase (NSE), somatostatin, calcitonin and thyroglobulin. Cells staining for NSE and somatostatin were present in 14 cases. In four cases large numbers of cells including oxyphil cells stained for NSE. Consecutive sections showed an identical staining pattern of these cells for somatostatin. Sections stained for calcitonin showed few or no positively staining cells. There were moderate numbers of NSE and somatostatin-containing cells in five of the cases, occasional cells in five and none in four cases. Electron microscopy confirmed neurosecretory-like granules within positively staining cells. Somatostatin is known to inhibit T3 and T4 production or release from thyroid cells by a direct action. We suggest, in Hashimoto's disease, somatostatin in paracrine cells serves as a local inhibitory neuroendocrine effector and could be causally related to the hypothyroid state.