Adamantinoma-like Ewing sarcoma is a rare variant of Ewing sarcoma with histologic and immunohistochemical evidence of squamous differentiation. This variant most commonly occurs in the head and neck region with a few cases reported in the long bones of the limbs. It may be associated with poorer clinical outcome and could pose a diagnostic challenge, particularly if it occurs in older patients or as a metastatic lesion. We present a case of Ewing sarcoma in the metatarsal of an 11-year-old boy that manifested adamantinoma-like morphology after neoadjuvant chemotherapy. Chemotherapy has been reported to induce neuronal maturation and rhabdoid morphology in cases of Ewing sarcoma, but no reports of treatment-induced squamous differentiation with P40/P63 expression have been demonstrated. This is also the first documented case treated with a pedicled osteocutaneous fibular transfer in a metatarsal malignancy, which is usually treated by either ray or below-knee amputation.
Adamantinoma-like Ewing sarcoma is a rare variant of Ewing sarcoma known to have histologic and immunohistochemical evidence of squamous differentiation. This variant most commonly occurs in the head and neck region with a few cases reported in long bones of the limbs. It may be associated with poorer clinical outcome and could pose a diagnostic challenge(s) particularly if it occurs in older patients or as a metastatic lesion. We present a case of Ewing sarcoma in the metatarsal of an 11 year old boy that manifested adamantinoma-like morphology after neo-adjuvant chemotherapy. Chemotherapy has been reported to induce neuronal maturation and rhabdoid morphology in cases of Ewing sarcoma, but no reports of treatment induced squamous differentiation with P40/P63 expression have been demonstrated. This is also the first documented case to use a pedicled osteocutaneous fibular transfer in a metatarsal malignancy, which is usually treated by either ray or below knee amputation.
Adamantinoma-like Ewing sarcoma is a rare variant of Ewing sarcoma known to have histologic and immunohistochemical evidence of squamous differentiation. This variant most commonly occurs in the head and neck region with a few cases reported in long bones of the limbs. It may be associated with poorer clinical outcome and could pose a diagnostic challenge(s) particularly if it occurs in older patients or as a metastatic lesion. We present a case of Ewing sarcoma in the metatarsal of an 11 year old boy that manifested adamantinoma-like morphology after neo-adjuvant chemotherapy. Chemotherapy has been reported to induce neuronal maturation and rhabdoid morphology in cases of Ewing sarcoma, but no reports of treatment induced squamous differentiation with P40/P63 expression have been demonstrated. This is also the first documented case to use a pedicled osteocutaneous fibular transfer in a metatarsal malignancy, which is usually treated by either ray or below knee amputation.
Background: Adamantinoma-like Ewing sarcoma is a rare variant of Ewing sarcoma known to have cytokeratin expression and squamous differentiation. It occurs more commonly in the head and neck region with only a few cases reported in long bones of the limbs. It also harbours EWSR1-FLI1 gene fusion which is required for the diagnosis of Ewing sarcoma. We present a case of Ewing sarcoma that manifested Adamantinoma-like morphology only post chemotherapy. Chemotherapy has been reported to induce neuronal maturation and rhabdoid morphology in cases of Ewing sarcoma, but no reports of treatment induced squamous differentiation with P40/P63 expression have been demonstrated to date.Case presentation: An 11 year old boy presented with a one year history of an enlarging painless mass over the left first metatarsal. Initial biopsy showed Ewing sarcoma with typical morphological features and EWSR1 rearrangement confirmed on fluorescent in-situ hybridization. The patient underwent neo-adjuvant chemotherapy and a subsequent wide local excision with an ipsilateral pedicled osteocutaneous fibula transfer. Subsequent histological examination showed frank squamous differentiation in the soft tissue component with keratin pearl formation and P40/P63 expression which was not observed in the initial biopsy and is compatible with Adamantinoma-like Ewing sarcoma.Conclusion: This case describes Adamantinoma-like Ewing sarcoma with P40/P63 expression after neo-adjuvant chemotherapy treatment. This immunophenotype was not apparent on the initial biopsy. It remains uncertain as to the reason for this change. This variant carries a poorer clinical outcome compared to the more conventional variant and could pose a diagnostic challenge(s) particularly if it occurs in an older patient or as a metastatic lesion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.