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Histopathologists in the current environment of medical negligence and litigation are more likely to use immunohistochemical investigations in their day-to-day practice to support their diagnosis and avoid future litigation. The caveat is that relying on immunohistochemistry is a double-edged sword and pathologists should be familiar with its limitations. We present a case of primary malignant peritoneal mesothelioma with an unusual immunohistochemical profile-desmin positive, EMA negative-and wish to highlight the importance of cautiously interpreting immunohistochemistry profiles when they do not fit the clinical history and histological appearance.

Background: Superficial acral fibromyxoma (SAF) remains poorly recognized by general pathologists and dermatopathologists, partly attributable to its relatively uncommon occurrence and recent documentation., Objectives: To examine a series of SAF and document the U.K. experience with this new entity., Methods: We reviewed 771 tumours reported between 1970 and 2006 in seven different U.K. hospitals and coded as myxoma, not otherwise specified (NOS), fibroma (NOS) or dermatofibroma (NOS) presenting at acral sites. Forty-one cases of SAF were studied., Results: The patients comprised 27 men and 14 women, age range 19-91 years (mean 50, median 47), presenting with a solitary mass or nodule with a mean size of 1.92 cm. The common clinical sites were the toes (n=29) and fingers (n=11) as well as the palm (n=1), with more than 75% of cases close to or involving the nail bed. All cases presented with a painless mass except for four cases where pain was the presenting complaint. A history of trauma was reported in only two cases. Histologically, all cases presented as proliferation of spindle-shaped and/or stellate cells with a storiform and fascicular pattern embedded in a fibromyxoid/collagenous stroma with conspicuous mast cells. Multinucleated cells were observed (n=22), increased number of blood vessels in the stroma and extravasation of red blood cells (n=4). The characteristic immunophenotype was CD34+, CD99+/-, epithelial membrane antigen+ focally/-, S100-, desmin-, smooth muscle actin-, HMB45- and cytokeratin-., Conclusions: We describe a large series of 41 cases of SAF showing that it is a distinct entity with typical clinical, histological and immunohistochemical features. Follow-up was available only in 12 patients, precluding a firm comment on recurrence. However, complete excision and follow-up review is recommended.

Background: Colloid cysts of the third ventricle are rare benign intracranial non-neoplastic cysts. Headache is the most common symptom. We present a case of sudden death due to colloid cyst in a 17 year old female who had symptoms of intermittent headaches., Case Presentation: A 17 year old female presented with intermittent mild headaches for a period of two years. She complained of severe headache in the night and was found unresponsive the next morning. Resuscitation team was called on site but the patient was already dead. At post mortem examination a dilated ventricular system was found with a colloid cyst of the third ventricle., Conclusion: This report highlights the difficulty in the diagnosis and importance of recognizing colloid cyst of the third ventricle which should be in the differential diagnosis of headaches in children and young adults and of hydrocephalus at autopsy.