Pilomatrixoma is the only skin appendage tumour showing predominantly hair matrix differentiation. Rarely, aggressive or malignant variants are reported in the literature. We report a case of a 44-year-old male with multiple pilomatrixomas, one of which grew rapidly, recurring several times. Histological examination of this tumour showed predominantly hair matrix differentiation but also abortive hair follicle formation with pilar keratinization reminiscent of a trichoepithelioma. Numerous mitoses and moderate cellular pleomorphism were present, associated with infiltration of subcutaneous skeletal muscle and vascular invasion.
Microbiological and electron microscopy studies were carried out on rectal biopsy specimens and faecal samples from eight practising male homosexuals and five heterosexual controls. Rectal spirochaetosis was present in five of the eight homosexual men. The organism was cultured and morphologically identified as a large anaerobic host associated treponeme. The degrees of infestation and depletion of microvilli were also measured. The results are discussed in relation to the possible clinical importance of rectal spirochaetosis.
Nucleolar organizer regions (NOR) are loops of DNA that transcribe ribosomal RNA; they can be easily identified in formalin fixed paraffin embedded tissue using a silver (Ag) method. It has been suggested that the number of AgNOR per cell can differentiate between benign and malignant melanocytic lesions of skin. We have studied 29 Spitz nevi (SN) and 39 invasive malignant melanomas (MM) by the same silver method. SN showed between 1.0 and 1.6 AgNOR per cell with a mean of 1.2. MM counts ranged from 1.2 to 4.2 with a mean of 2.0. It is concluded that the AgNOR method cannot reliably differentiate SN from MM; however, a count of more than 2.0 AgNOR per cell would favor a diagnosis of MM rather than SN.
The hypothesis is presented that fractal geometry, and the fractal dimension in particular, is likely to be a more useful method of image analysis in histopathology than the use of regular Euclidean geometry. The concept of the fractal dimension is described and it is suggested that many human tumours have a fractal structure over a wide range of scales. It is postulated that the fractal dimension will be useful in discriminating between different diagnostic categories and may also allow more precise prognostic stratification within single diagnostic groups.
Two examples of a variant of benign spiradenoma are reported, both characterized by their large size and high degree of vascularity. The results of studies using light microscopy, transmission electron microscopy and immunohistology are described. The relationship of this unusual variant to other spiradenomas and their eccrine sweat gland origin is discussed. The possible misdiagnosis of this rare type of spiradenoma is emphasized.
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