The three-dimensional topography of the environment is a potentially important source of orienting information for animals, but little is known about how such features affect either navigational behaviour or the neural representation of place. One component of the neural place representation comprises the hippocampal place cells, which show location-specific firing that can be oriented by directional cues in the environment. The present study investigated whether a simple topographical feature, terrain slope, could provide such orienting information to place cells. Place cells were recorded as rats explored a tilted (30 degrees) square box located in the centre of a dark, curtained and visually symmetrical circular enclosure. The orientation of the tilted surface was varied, first in conjunction with that of a visible cue card (to stabilise the system) and then in the absence of the cue card, when the slope of the box was the only remaining stable polarising cue in the environment. In the latter condition, place fields continued to be reliably oriented by the slope. Thus, terrain slope provides sufficient orienting information to set and probably maintain the orientation of the hippocampal place system. This may explain previous behavioural observations that spatial orientation is improved when slope information is available.

Key Points Question What is the rate of incidental skin cancer detection in urgent skin cancer clinics, and are incidental cancers more likely to be detected in patients with a clinically suspicious index lesion than in those without? Findings In a cohort study including 4726 patients, 1117 malignant lesions were detected, 22% of which were identified incidentally by total body skin examinations corresponding to an incidental lesion detection rate of 5.1%. Detection of a malignant incidental lesion by total body skin examinations was significantly more likely in patients presenting with an index lesion suspicious for malignancy, compared with patients who presented with index lesions judged to be clinically benign. Meaning The findings of this study suggest that total body skin examinations may be useful for detecting incidental skin cancers and that patients with suspicious index lesions should be prioritized.

Basosquamous carcinoma (BsC) is a controversial entity and both a diagnostic and therapeutic challenge. BsC has mixed histopathological characteristics of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC and SCC display characteristic histopathology and behaviour; on the other hand, BsC is a rare tumour, which has variable morphology and displays less predictable behaviour. An early diagnosis of BsC is important due to the particularly aggressive nature of the tumour, the increased likelihood of recurrence and the potential for metastasis. Here, we present a case of BsC presenting as an extensive ulcer on the back. The case highlights the aggressive nature of the tumour and variation in appearance. It is important for all clinicians to be aware of this diagnosis so that the urgency of adequate biopsy in specialist clinics is not underestimated.