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A method and apparatus are disclosed for testing the dropout response of a magnetic recording medium by detecting and counting dropouts present on the recorded magnetic recording medium. A pulse (which may be on any one of a number of fundamental frequencies) is recorded on the magnetic storage medium. When the level of the reproduced tone is below a given amplitude level, a timing apparatus consisting of a linear ramp generator and comparator is activated. The comparator produces an output pulse each time the level of the signal produced by the linear ramp generator falls below a given amplitude level. The production of each output pulse reflects that the dropout has persisted for a reference time unit. The number of pulses produced during any given dropout is a measure of the duration of the entire dropout in reference time units. The total number of pulses produced by the comparator is stored in a counter, the count reflecting the dropout performance of the magnetic storage media.

Background: The dermoscopic features of classic patch stage mycosis fungoides (MF) have been described, but data on plaque and tumoral stage as well as rarer MF subtypes is limited. Objective: To evaluate dermoscopic morphology and dermoscopic-pathological correlations of classic MF stages and investigate dermoscopic features of MF variants. Methods: Patients with histopathologically confirmed lesions of classic MF (patch, plaque and tumoral stage) or folliculotropic, erythrodermic and poikilodermatous MF were included. Standardized evaluation of dermoscopic pictures of the included MF variants and comparative analysis and dermoscopic-pathological correlation assessment of different stages of classic MF were performed. Results: A total of 118 instances were included (75 classic MF, 26 folliculotropic MF, 9 erythrodermic MF and 8 poikilodermatous MF). Linear/linear-curved vessels and white scales in the skin furrows were significantly associated with patch-stage MF, while clustered dotted vessels were related to plaque-stage MF and peripheral linear vessels with branches, ulceration and red globules separated by white lines to tumour-stage MF. Moreover, patchy white scales were significantly more common in patches and plaques compared to tumours, whereas focal bright white structureless areas were related to plaque and tumoral stage. Vessels histopathologically corresponded to dilated vascular structures in the dermis, orange structureless areas to either dermal hemosiderin (patch/plaque stage) or dense cellular infiltration (tumours), bright white lines/structureless areas to dermal fibrosis and ulceration to loss of epidermis. The main dermoscopic findings of folliculotropic MF were lack of hairs, dilated follicles and follicular plugs, while erythrodermic MF was mainly characterized by linear/dotted vessels, patchy white scales and focal orange structureless areas and poikilodermatous MF by focal white and brown structureless areas, white patchy scales and brown reticular lines. Conclusion: Dermoscopy may allow a more precise characterization of classic MF and reveal clues suggestive of the main MF variants.

Background Primary cutaneous B-cell lymphomas (PCBCLs) are frequently misdiagnosed, and a biopsy is needed to attain the correct diagnosis. Objective To characterize the dermoscopic features of PCBCL. Methods In this retrospective observational study, we analysed the pathology reports of 172 newly diagnosed PCBCL for the initial clinical differential diagnosis. The dermoscopic images of 58 PCBCL were evaluated for dermoscopic features. Two dermoscopy experts, who were blinded to the diagnosis and the study objective, evaluated images from 17 cases for a dermoscopic differential diagnosis. Results Of 172 biopsy-proven PCBCL lesions, cutaneous lymphoma was suspected by the clinician in 16.3%; the leading diagnosis was basal cell carcinoma in 17.4%, and other skin neoplasms in 21%. Studying 58 PCBCL dermoscopic images, we most frequently identified salmon-coloured background/area (79.3%) and prominent blood vessels (77.6%), mostly of serpentine (linear-irregular) morphology (67.2%). Dermoscopic features did not differ significantly by subtype or location. Blinded evaluation by dermoscopy experts raised a wide differential diagnosis including PCBCL, arthropod bite, basal cell carcinoma, amelanotic melanoma and scar/keloid. Conclusions Two dermoscopic features, salmon-coloured area/background and serpentine vessels, are frequently seen in PCBCL lesions. These characteristic dermoscopic features, although not specific, can suggest a possible diagnosis of PCBCL.