Intranodal myofibroblastoma is an uncommon benign mesenchymal tumour of lymph nodes which was first described in May 1989. All the cases described to date have presented exclusively in the groin, a feature which has been regarded as distinctive. Two new cases are presented herein, both of which arose in the submandibular region of middle-aged females. Both lesions showed histological features marginally different from the cases originally described, which may reflect their different anatomical location. Immunohistochemical staining revealed positivity for muscle-specific actin (HHF 35), as previously described, and ultrastructural examination in one case confirmed the presence of myofibroblasts. The data presented suggest that this distinctive lesion has a broader clinicopathological spectrum than previously realised.

The pigmented neuroectodermal tumour of infancy is a rare neoplasm of uncertain histogenesis which, in the majority of cases, arises in the maxilla and pursues a benign course. Currently, it would be classified in the group of peripheral primitive neuroectodermal tumours. Histologically it is composed of two principal cell types: neuroblast-like and melanocyte-like. Three typical cases are presented herein, which appear to be the first examined with a panel of antibodies. The neuroblast-like cells labelled positively for neurone-specific enolase but were negative for S-100, neurofilaments, glial fibrillary acidic protein, vimentin, cytokeratin, epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA). The melanocyte-like cells stained positively for neurone-specific enolase, vimentin and cytokeratin but were negative for S-100, neurofilaments, glial fibrillary acidic protein, EMA and CEA. The significance of these findings is discussed in the light of previous suggestions about the differentiation that these tumours show.

Summary A murine monoclonal antibody PASE/4LJ to prostatic acid phosphatase (PAP) was used to immunostain a wide variety of sections of benign and malignant tissues (654 blocks). Non-neoplastic adult and fetal prostatic glands, primary and metastatic prostatic carcinomas, and scattered cells in prostatic and penile urethra were positive. Rat, dog and rabbit prostates were negative. Nine of 400 tumours of non-prostatic origin showed some positivity: 6/36 carcinoids, 1/9 islet cell tumours, 1/55 ovarian adenocarcinomas (serous) and one carcinosarcoma of the lung (epithelial portion). Positive staining was seen in islet cells in 4/5 specimens of normal pancreas, and in 4/9 blocks of normal pancreas surrounding a pancreatic tumour. Loops of Henle, maculae densae, and distal tubules in 10/10 fetal and 2/9 adult kidneys were also positive, with proximal tubules and collecting ducts negative. All other 159 blocks of non-neoplastic adult and fetal tissues were negative. The antibody was also affinity purified from ascitic fluid, and shown not to inhibit the enzyme activity of prostatic acid phosphatase.

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