Scintigraphic diagnosis, based on functional image interpretation, becomes more accurate and meaningful when supported by corresponding anatomical data. In order to produce anatomical images that are inherently registered with images of emission computerised tomography acquired with a gamma camera, an X-ray transmission system was mounted on the slip-ring gantry of a GEMS Millennium VG gamma camera. The X-ray imaging system is composed of an X-ray tube and a set of detectors located on opposite sides of the gantry rotor that moves around the patient along with the nuclear detectors. A cross-sectional anatomical transmission map is acquired as the system rotates around the patient in a manner similar to a third-generation computerised tomography (CT) system. Following transmission, single-photon emission tomography (SPET) or positron emission tomography (PET) coincidence detection images are acquired and the resultant emission images are thus inherently registered to the anatomical maps. Attenuation correction of the emission images is performed with the same anatomical maps to generate transmission maps. Phantom experiments of system performance and examples of first SPET and coincidence detection patient images are presented. Despite limitations of the system when compared with a state of the art CT scanner, the transmission anatomical maps allow for precise anatomical localisation and for attenuation correction of the emission images.

The histogenesis of cutaneous focal mucinosis (CFM) is controversial. Eleven cases of CFM (5F, 6M; mean age 51 years) from our routine files between 1986 and the present time have, therefore, been examined histopathologically and immunohistochemically. Histology revealed an increased number of fibroblast-like cells in early lesions, whereas they were diminished or predominantly at the margin in advanced ones. The myxomatous areas showed slight to absent reticulum formation. Similarly, elastic fibers were almost absent, and collagen fibers were fragmented and replaced by variable amounts of mucin. One specimen revealed an epithelial component within the lesion reminiscent of a poorly induced trichofolliculoma. Immunohistochemically, vimentin was consistently present and correlated with the number of fibroblast-like cells. A few (< 5%) CD34+ dermal dendritic cells (DDs) were focally seen within CFM. In contrast, FXIIIa+ DDs accounted for up to 30%. Fibroblast-like cells were negative for S-100 protein, Leu7, desmin and alpha-SMA. The epithelial component within one of our specimens seems to have been induced by CFM and is a feature also seen in (angio)-myxomas. CFM appears to be a mesenchymally derived lesion composed predominantly of fibroblasts. DDs do not form the major cell component but rather seem passively incorporated.

SummaryErosive pustular dermatosis of the scalp (EPDS) is an inflammatory dermatosis of unknown etiology. Herein, we present a review of the disease and report our own clinical and histopathological experience in eleven patients. EPDS tends to spontaneously affect bald areas of the scalp in elderly individuals. A history of previous surgery at the same site -as observed in four of our patients -is common. Coronary artery disease, cerebrovascular insult, arterial hypertension, diabetes mellitus, and severe cases of cancer were frequent comorbidities. Most patients show an undulating clinical course despite topical anti-inflammatory treatment; in some individuals, the lesions heal with scarring. Histopathology reveals scaly crusts or erosions and granulation tissue-like changes in the dermis, evolving into a scar in more advanced stages. Apart from actinic/local damage, impaired immunity and microcirculation may be predisposing factors of the disease. Similar to pyoderma gangrenosum, EPDS must be considered in the context of nonhealing wounds in the elderly after the differential diagnoses mimicking EPDS have been ruled out. Given that previous or concomitant adjacent basal cell or squamous cell carcinoma is a common finding and that infiltrative variants extending beyond the clinically visible tumor may occur, histological mapping of the surrounding skin may be advisable in doubtful cases.

There are significant differences in the ability of commercial AC systems to reduce artifacts due to attenuation and scatter. These differences are partly the result of non-AC factors (collimation, orbit, etc). In general, systems that generated high-quality attenuation maps yielded the best results.

Atypical cutaneous fibrous histiocytoma is a rare variant of dermatofibroma/fibrous histiocytoma characterized by striking atypia, thus resembling atypical fibroxanthoma. We studied 9 examples of ACFH histopathologically and immunohistochemically to investigate the nature of these atypical cells. Histology revealed ill-defined skin nodules, which were polypoid in 6 cases. A minority of mononuclear and giant cells (< 5%) revealed striking pleomorphism and showed large nuclei with prominent nucleoli. Immunohistologically, the atypical cells expressed vimentin, but were negative for S-100 protein, the keratin marker MNF116, alpha smooth muscle actin, CD34, factor XIIIa, and monocyte/macrophage markers Ki-M1p, KP1 (CD68), and MAC387. Positivity for MiB1 was very modest (< 1%) and limited to small- and medium-sized, inconspicuous cells. Multinucleate giant cells proved to be heterogenous, on one hand cells with differentiation toward macrophages with positivity for Ki-M1p and KP1, on the other toward fibroblasts positive for vimentin only. These immuno-histochemical results for differentiation markers in atypical cutaneous fibrous histiocytoma are similar to our previous findings and data in atypical fibroxanthoma; MiB1 helps to separate these entities from each other as the latter shows a very high proportion of proliferative atypical cells corresponding to the numerous mitoses seen in routine sections.