Fibrolipomatous hamartoma of the thoracic skin.
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Fibrolipomatous hamartoma (FLH) is a benign proliferation characterized by the presence in the deep dermis of mature adipose tissue lobules separated by bundles of fibrous tissue. The variant best known to internists, neurologists and radiologists is the perineural FLH, which is localized around nerves, most frequently the median nerve, followed by the ulnar and sciatic (5). The variant best known to dermatologists and pediatricians is the precalcaneal FLH, which is evident from the earliest stages of life with a medial precalcaneal swelling of parenchymatous consistency and of little clinical importance. It tends to regress spontaneously, but even when it does not regress, it does not hinder walking (4). Rarer variants of FLH can affect the respiratory tree, localizing to the nasopharynx (3), the bronchi (1), or the lung (7).
Although the most frequently affected skin site is the medial precalcaneal one, FLHs localized always in the calcaneal area, but posteriorly, have been described (6). Both in the latter and in the more frequent one located in the classical site, the most accredited pathogenetic hypothesis is a failure to regress of the pericalcaneal, fetal life adipose tissue. However, this hypothesis does not explain the location to the trunk of the current case.
From a diagnostic point of view, when FLH is localized in the classical site, the diagnosis is clinical and a biopsy is not necessary. In cases located elsewhere, ultrasound is useful, showing hypoechoic lobules of the same echogenicity as the adipose tissue, separated and surrounded by hyperechoic bands that correspond to the dermal connective tissue (2).
The benignity of the lesion, the absence of functional damage, the lack of esthetic damage, and the tendency to spontaneous regression make any therapy useless, once the diagnosis has been ascertained.