“Alopecic and Aseptic Nodules of the Scalp” and “Pseudocyst of the Scalp”: 2 Different Conditions or One Single Entity?

The first of the 2 terms used was: “Pseudocyst of the scalp” and was first described in 1992 by Iwata et al. [1] in a report of 19 Japanese patients presenting with alopecia and a solitary subcutaneous tumor with a histologically ill-defined cyst wall. Some years later, in 1998 in France, Chevallier [2] reported 3 cases described in French as 'noninfectious abscess of the scalp with alopecia'. In 2011, Abdennader et al. [3] reported 15 cases with similar morphological features to those of pseudocyst of the scalp; however, the condition was referred to as "alopecic and aseptic nodules of the scalp" because pseudocyst formation was not always present. From our point of view both diseases share so many clinical factors that should be considered one single entity.