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.
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