Pseudolipomatosis Cutis: A Retrospective Case Series of Skin Biopsies Showing a Distinctive Vacuolar Artifactual Change.

Pseudolipomatosis cutis is a distinctive artifact characterized by the presence of adipocyte-like vacuoles in the biopsy specimens. We describe this change in a series of skin biopsies clustered over 2 periods, November 2017-December 2017 and February 2019. Hematoxylin and eosin-stained sections from 21 skin biopsies were examined by 2 dermatopathologists. Variable-sized vacuoles were noted in the epidermis, dermis, and/or subcutaneous fat in all biopsies. Vacuoles were seen in the stratum corneum in 2 biopsies, epidermis in 15 biopsies, papillary dermis in 19 biopsies, reticular dermis in 20 biopsies, and subcutis in 9 biopsies. The vacuoles resembled a true histological change in many biopsies: vacuolated keratinocytes (n = 6), basal cell vacuolization (n = 6), foamy histiocytes (n = 12), and adipocytes (n = 20). Other changes included dermal collagen sclerosis and empty ectatic vascular channels. The clustering of this peculiar change in biopsies from patients with unrelated skin diseases that stopped on changing the formalin solution in both instances suggests that it is an artifactual change due to improper tissue fixation.