Introduction: chondroid lipoma is a rare, benign lipomatous tumor that may be mistaken histologically for a liposarcoma or chondrosarcoma. Herein, two cases of chondroid lipoma are reported in two Egyptian females aged 38 and 51 years and literature about this rare tumor briefly reviewed with discussion of diagnostic criteria that may help distinguish it from other tumors with overlapping histologic features. case series: the tumor was subcutaneous in both cases. One was located in the right knee area, the other in an infra-mammary location on the right side of the chest. Grossly, both neoplasms were encapsulated and exhibited a nodular, myxoid cut surface. Histologically, they consisted of an abundant myxoid and chondroid stroma interspersed by small round cells with eosinophilic or vacuolated cytoplasm, signet ring lipoblast-like cells, adipocytes and foci of mature adipose tissue. Immunohistochemically, diffuse reactivity of the neoplastic cells for vimentin and variable reactivity for s-100 protein were present in both cases. One case also showed focal immunoreactivity for cD68. the

BackgroundHyalinizing clear cell carcinoma (HCCC) is a rare low-grade tumour of salivary glands that was first described as a distinct entity in 1994 by Milchgrub et al. EWSR1-ATF1 fusion was found to be specific for this tumour. The majority of the reported cases of HCCC arise from minor salivary glands within the oral cavity. Primary HCCC of the paranasal sinus is extremely uncommon. To our knowledge, only three cases have been reported in the English literature. Herein, we present a case of HCCC of the posterior ethmoid/maxillary sinus.Case presentationA 63-year-old lady who presented with a long history of epistaxis. CT scan revealed a destructive mass in the left ethmoid/posterior maxillary sinus extending to the nasal cavity. Surgical excision was done and microscopic evaluation showed a tumour composed mainly of nests of clear epithelial cells separated by fibrocellular and hyalinized septa with extensive bone destruction. The tumour cells expressed CK5/6, EMA and p63 immunohistochemically but were negative for S100 protein, PAX-8, RCC and CK7. Sinonasal renal cell–like adenocarcinomas, myoepithelial carcinoma and metastatic renal cell carcinoma were excluded by radiological and immunohistochemical studies. Fluorescence in situ hybridization analysis revealed an EWSR1 gene rearrangement. Postoperative radiation was administrated and the patient did not show recurrence or distant metastasis 4 months after the surgery.ConclusionHead and neck region have many tumours that demonstrate clear cell changes on histology. Thus, the differential diagnosis for HCCC is wide. Awareness of this rare entity and the possibility of it is arising in unusual location is necessary. EWSR1-AFT1 fusion, a consistent finding in HCCC, can be used to confirm the diagnosis.