Anisometric Cell and Dysplastic Lipomas in a Retinoblastoma Patient

Abstract

Anisometric cell lipoma (ACL) and dysplastic lipoma (DL) are underrecognized subtypes of benign lipomatous tumors, with wide variation in cell size, microscopic fat necrosis, and no or mild nuclear changes (DL). ACL/DL appear more commonly in retinoblastoma patients, in whom an increased incidence of lipomas has been established. The occurrence of ACL/DL in retinoblastoma patients suggests that RB1 aberrations play a role in its pathogenesis, similar to spindle cell/pleomorphic lipoma. In this article, we present a patient with a history of retinoblastoma with multiple lipomas histologically consistent with ACL/DL. Analysis of the lipomas supports involvement of RB1 in the development of ACL/DL. Dysplastic changes were only seen in a single lipoma, which harbored an additional TP53 mutation. While providing further support for the occurrence of ACL/DL in retinoblastoma patients, we also suggest that DL is an ACL with TP53 mutation.

‘I Can’t Keep Up!’: an update on advances in soft tissue pathology occurring after the publication of the 2020 World Health Organization classification of soft tissue and bone tumours

“…These authors speculated that MDM2 mRNA up‐regulation in dysplastic lipoma might be the result of p53 activation. An interesting association between dysplastic lipoma and childhood retinoblastoma has also been noted 79,83,84 …”

“…An interesting association between dysplastic lipoma and childhood retinoblastoma has also been noted. 79,83,84 As should be obvious, the clinical and immunohistochemical features of dysplastic lipoma (e.g. occurrence in the neck/shoulders of men, CD34-positive spindled cells, and RB1 loss) are strikingly similar to those of spindle cell/pleomorphic lipoma.…”

Anisometric Cell/Dysplastic Lipomas in a Retinoblastoma Survivor: Report of a Case with Review of the Literature

“…We however note the suggestions made by den Bakker. 5 Overlapping features between AC/DL and spindle cell lipoma, such as predilection for the shoulder and back, histological features, and underlying genetic aberrations begs the question: are both these entities the same? As Agaimy pointed out for anisometric cell lipoma (not dysplastic lipoma), these can be considered a "fat-only" spindle cell lipoma, 2 although we agree that consistent paucity or absence of fibromyxoid stroma in AC/DL argues against this.…”

Well‐differentiated lipomatous neoplasms with p53 alterations: a clinicopathological and molecular study of eight cases with features of atypical pleomorphic lipomatous tumour

“…In this regard, it is notable that, whereas one study of 'dysplastic lipoma', an atypical well-differentiated adipocytic neoplasm that may represent a 'fat-rich' variant of ASCLT, 19 demonstrated immunohistochemical p53 expression in the atypical neoplastic cells and no evidence of TP53 mutation in five cases analysed with Sanger sequencing, 20 a more recent report described a 'dysplastic lipoma' bearing a TP53 mutation arising in a retinoblastoma patient. 21 More clinicopathological and molecular genetic studies of ASCLT and dysplastic lipoma are required to better understand their relationships with APLT and with each another.…”