Loss of Retinoblastoma Protein Expression in Spindle Cell/Pleomorphic Lipomas and Cytogenetically Related Tumors: An Immunohistochemical Study With Diagnostic Implications

Liposarcomas: diagnostic pitfalls and new insights

Liposarcomas represent the most common histotype among soft tissue sarcomas. However, liposarcomas in fact constitute a heterogeneous group of distinctive lesions that pose several diagnostic difficulties. The current World Health Organization classification of soft tissue and bone tumours recognizes four major liposarcoma subtypes: (i) atypical lipomatous tumour/well-differentiated liposarcoma; (ii) de-differentiated liposarcoma; (iii) myxoid liposarcoma; and (iv) pleomorphic liposarcoma. These four main subgroups are characterized by distinctive morphologies, unique genetic findings as well as distinct clinical behaviour. Accurate classification requires the integration of morphological, immunohistochemical and (in selected situations) genetic findings, and is essential for providing patients with the best available treatments. This review will focus upon the main diagnostic pitfalls encountered in the routine diagnosis of liposarcoma, underlining the diagnostic value of combining morphology with cytogenetics and molecular genetics.

Paratesticular cellular angiofibroma with atypical (bizarre) cells: case report and literature review

We report the extremely unusual occurrence of a cellular angiofibroma (CAF) with atypical (bizarre) cells in the spermatic cord. We present a 63-year-old man, who was referred to the Urology Service with a six-month history of a slowly growing painless nodule in the right inguino-scrotal area. The clinical impression was that of a lipoma. The mass was locally excised. Gross examination showed a well-circumscribed neoplasm attached to the spermatic cord and measuring 5cm in the greatest dimension. Microscopic examination of the tumor showed the appearance of CAF with scattered severely atypical (bizarre) cells distributed throughout the lesion. By immunohistochemistry, atypical cells showed diffuse expression of p16, CDK-4, CD34 and vimentin. Keratin AE1/AE3, S-100 protein, p53, and epithelial membrane antigen were negative. The patient is free of disease two months after tumor excision. To the best of our knowledge, this is the third case of CAF with atypical (bizarre) cells occurring in the paratesticular area. Pathologists should be aware of this morphological variation of CAF to avoid misdiagnosis and over-treatment.