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From time to time, we come across linear skin lesions. This can be very helpful diagnostically as there is a limited range of possible diagnoses. A careful history and examination of the morphology of the lesions usually sorts them out.
For each of the nine cases, study the image(s) and then answer the questions. You can click on the image to view a larger version if required.
Each case should take approximately 2 minutes to complete. There is a list of suggested further reading material at the end of the quiz.
Name these linear skin lesions.
Linea nigra
What is the cause?
The dark line down the centre of a pregnant abdomen is called linea nigra, in contrast to the less-obvious non-pregnant linea alba. The pigmentation change may be due to increased levels of melanocyte stimulating hormone, oestrogen and progesterone during pregnancy, which may also result in darkening of the nipples, axillae and perineum and face (melasma). Although linea nigra may be normal for a non-pregnant sun-exposed dark-skinned individual, recent pigmentary change might be a sign of Nelson syndrome (ACTH-secreting pituitary tumour).