Clinicopathologic Features of Two Rare Cases of Dedifferentiated Adamantinomas, Including Diagnostic Implications

Abstract

A dedifferentiated adamantinoma is a rare subtype of an adamantinoma, associated with a relatively aggressive clinical course, with less than 10 such cases reported so far. A 25-year-old-male presented with pain in his right leg of 1-year duration. Imaging disclosed a well-defined lytic, destructive lesion in his proximal tibia with a cortical break and a soft tissue component. Microscopic examination of the biopsy and resected specimen showed nests and clusters of atypical epithelial cells, along with significant areas showing markedly pleomorphic and spindly sarcomatous cells with interspersed mitotic figures and areas of stromal hyalinization. By immunohistochemistry, the areas of epithelial differentiation showed intense positivity for cytokeratin and p63, whereas the sarcomatous areas showed reduced to absent immunostaining. A 51-year-old lady presented with a recurrent tumor in her right tibia, which was initially diagnosed as an adamantinoma, along with metastatic lesions in her lung. Microscopic examination of the recurrent and metastatic tumors showed areas of epithelial differentiation along with spindly sarcomatous cells, arranged in fascicles. By immunohistochemistry, the areas of epithelial differentiation showed positivity for pan cytokeratin. Additionally, p63 was diffusely positive. p53 showed diffuse and intense staining pattern in the sarcomatous component (dedifferentiation). While the first case is disease-free, the second case is on follow-up. The 2 cases of dedifferentiated adamantinoma further confirm the rare occurrence of this tumor in our population. Its correct diagnosis has treatment implications. Differential diagnoses and literature review of similar reported cases are also presented in this article.

Osteosarcoma arising in a case of osteofibrous dysplasia of tibia with classic adamantinoma: A case report and literature review

“…Of these 11 reported cases, six died of the disease. 6 For our case, upon follow-up at 1 The relationship between OFD, ADM and dedifferentiated ADM is not clear yet. In our case, this co-existence of the diseases may support the hypothesis of OFD being a precursor of ADM, and they may be part of a spectrum of diseases with multistep neoplastic transformation.…”

“…There is no report of cases with concomitant OFD, ADM and osteosarcoma, but there are 11 cases of ADM with sarcomatous change reported in the literature. [4][5][6]27 Hazelbag et al 5 first described three ADM cases with loss of epithelial differentiation of tumour cells as 'dedifferentiated' ADM in 2003, with deposition of chondroid and osteoid matrix observed. The term 'dedifferentiation' means loss of epithelial differentiation and replacement by a sarcomatous component, similar to an epithelial-mesenchymal transition.…”

“…To date, there is no report of OFD with malignant transformation to osteosarcoma, but there are a few papers about adult ADM cases with sarcomatous transformation. [4][5][6] In this article, we present an adolescent case with concomitant OFD, ADM and osteosarcoma of the tibia.…”

Adamantinoma with a Prominent Spindle Cell Component Mimicking Intraosseous Synovial Sarcoma: Clinicopathological Features of Six Tumors

“…The lack of pleomorphic sarcomatous cells ruled out the ultra-rare, dedifferentiated adamantinoma, which contains a variable spindle cell component. 11, 12…”

Outcome of osteofibrous dysplasia-like versus classic adamantinoma of long bones: a single-institution experience

“…AD has a wide range of histological types, including classic and OFD-like subtypes [ 14 ]. A recently reported new subtype called dedifferentiated AD has a high-grade sarcoma component in a background of epithelial and osteofibrous cells [ 16 – 18 ]. The proportions of epithelial and osteofibrous components are used to differentiate OFD-like AD and classic AD.…”