Lipomatous metaplasia of superficial dermis

Approach to the so-called "Invisible Dermatosis": When Subtle Histopathological Findings Guide Diagnosis

ABSTRACT

Invisible dermatosis is a concept that can be applied either to clinical or histopathological findings. We will focus on the dermatopathological aspect of this invisible dermatosis that can be seen as dermatosis with subtle histopathological findings that are mandatory to known to stablish the diagnosis. With a proper approach facing in depth the different skin layers from stratum corneum to subcutaneous tissue combined with some especial stains, special investigations and mostly a proper clinicopathological correlation, the problem of missing out a diagnosis can be decreased. We will review the general aspects for diagnosis and the peculiar findings of an in-depth review of them because it is important to note that minor changes on a skin biopsy do not mean it is disease free. We will review classic clues, we will add some new useful ones, and we will also provide a guide on the special stains helpful, such as periodic acid-Schiff when facing fungi, orcein-Giemsa and van Gieson when altered elastic fibers are suspected, or Pearl and Masson Fontana when an altered skin pigmentation is suspected.

Graft-versus-host disease-associated angiomatosis with striking lipomatous metaplasia

Sclerodermatous graft-versus-host disease (GvHD) is one of the many clinicopathological variants of chronic GvHD. One of the rarest forms of this variant is GvHD-associated angiomatosis (GvHD-AA). We describe the case of a 62-year-old male with sclerodermatous GvHD who presented, in consecutive years, two different lesions that showed characteristics of GvHD-AA. The first lesion fitted perfectly with the previously known features of this rare entity. However, the second lesion was more interesting, as the angiomatoid lesion was surrounded by newly appeared adipocytes, something not previously described. The appearance of this peculiar adipose tissue may be explained as related to an important dermal atrophy, as a concomitant appearance of a lipomatous nevus and GvHD-AA, or, finally, as mature adipose tissue related to a previous inflammatory process, that is, lipomatous metaplasia. Both lesions were diagnosed as GvHD-AA, and the second one was considered to be associated with dermal lipomatous metaplasia. We also considered whether hypoxia could be related to both lesions. In the present report, we review previously published cases of GvHD-AA and discuss the different hypotheses that could explain the appearance of metaplasia associated with the second lesion.

Intradermal Band-like Lipomatous Metaplasia Can Be Associated With the Regression of Overlying Skin Neoplasms: A Clinicopathologic Study of 20 Cases

ABSTRACT

Lipomatous metaplasia has been rarely reported in both neoplastic and inflammatory dermatological disorders. Most neoplastic cases show the lipomatous change within the tumor silhouette, but band-like lipomatous metaplasia in the dermis under tumors has not been well-described. The aim of this study was to reveal the characteristics and relationship of intradermal band-like lipomatous metaplasia and coexisting skin tumors. A total of 20 cases with intradermal band-like lipomatous metaplasia were retrieved from 10,992 archive cases between April 1997 and March 2020 at Hyogo Cancer Center, and subjected to a detailed clinicopathologic analysis. Nine (45%) patients had superficial variant basal cell carcinoma as a coexisting neoplasm. Eight (40%) patients had squamous cell carcinoma, 5 of which were in situ. The remaining 3 (15%) cases were invasive extramammary Paget disease. All 20 cases showed at least one of 3 signs of tumor regression, namely, partial loss of overlying neoplasia, significant inflammatory infiltrate under the tumor, and fibrosis around the tumor. We concluded that intradermal band-like lipomatous metaplasia could be seen in association with the regressing process of cutaneous superficially-spreading neoplasms.