Answer to: “Re: Intramuscular lipomas: Large and deep benign lumps not to be underestimated. Review of a series of 51 cases”

In relation to the points highlighted by Dr. Ivan Chernev regarding our work, firstly we would like to thank him for their relevance. As we mentioned in the beginning of the Discussion, “benign lipomatous tumors encompass a wide and complex variety of lesions”. Having said this, the term “deep-seated lipoma” is indeed more suitable and less “controversial” to refer to a pathology which is not perfectly defined and which probably includes other entities in addition to intra- and intermuscular lipomas, like hibernomas and others.

In our series, in the Results section, we describe 78% of the intramuscular lipomas and 20% of the intermuscular lipomas based on MRI findings, since in our hands they were both clinically and histopathologically undistinguishable. In any case, distinction through imaging is not simple, given that, in the same patient, a tumor may appear, or be, intramuscular in one section and intermuscular in another. Since the approach was fundamentally clinical and general, in the second paragraph of the Discussion we pointed out that we would be using the term “intramuscular lipoma” to refer to entities including tumors in deep locations with respect to the fascia, established within a muscle or between muscle groups. The precision of distinguishing and analyzing them separately, as done by Fletcher and Martin Bates in 1988¹ and previously by Kindblom et al.,² is very accurate, although this was not the objective of our study. In fact, in the section on the limitations of the study, we insist on the decision to group them all under the term “intramuscular lipoma”. The proportion between males and females in our series was indeed close to 3/1. Although we did not specify it, after reviewing this information based on the comments received, the proportion was even greater in favor of males in the group of intramuscular lipomas. Additionally, and supporting the epidemiological data, since the publication of the article we have intervened 4 new patients with deep-seated lipomas: 1 female (an intermuscular lipoma) and 3 males (3 intramuscular lipomas).

We completely agree with the third and fourth observations. Regarding the reference to recurrences, the low incidence in our series should be interpreted with natural caution due to the limitation of a mean follow-up of 33 months.

Lastly, we agree on the importance of adding to the conclusion of our work the convenience of distinguishing the different types of deep-seated lipomas, as well as the need to continue extending the knowledge about this pathology.

Level of evidence

Level of evidence V.