Parosteal osteosarcoma with low grade chondrosarcoma and liposarcoma components. A rare histologic variant. Case report and literature review.

INTRODUCTION: conventional parosteal osteosarcoma is an uncommon malignant bone tumor, comprising 4% of all osteosarcomas. Although rare, parosteal osteosarcoma is the most common type of osteosarcoma of the bone surface. We present the clinical, histological and imaging characteristics of a rare histologic variant of a parosteal osteosarcoma, review the literature and emphasize the importance of radio-pathological correlation as well as the interpretation of a representative biopsy in order to obtain the correct diagnosis. CASE REPORT: a 36-year old woman began her condition one year prior to admission to the hospital with increased volume in the left knee and pain. Image studies showed a juxtacortical heterogeneous tumor localized on the posterior surface of the distal femoral metaphysis. An incisional biopsy was performed, with the diagnosis of a Parosteal Osteosarcoma and a wide surgical resection was undertaken. According to the findings of the surgical specimen, the diagnosis of a Parosteal Osteosarcoma with low grade chondrosarcoma and liposarcoma components was made. The knowledge of this rare parosteal osteosarcoma variant can lead the orthopedic oncologists to avoid overlooking the adipose component and provide adequate surgical margins. CONCLUSION: we present the clinical, histological and imaging characteristics of a Parosteal Osteosarcoma with low grade liposarcoma and chondrosarcoma components.

INTRODUCCIÓN: el osteosarcoma parosteal convencional es un tumor óseo maligno poco común, que comprende el 4% de todos los osteosarcomas. Aunque es poco común, el osteosarcoma parosteal es el tipo más común de osteosarcoma de la superficie ósea. Presentamos las características clínicas, histológicas y de imagen de una variante histológica rara de un osteosarcoma parosteal, revisamos la literatura y enfatizamos la importancia de la correlación radio-patológica, así como la interpretación de una biopsia representativa para obtener el diagnóstico correcto. REPORTE DE CASO: mujer de 36 años inició su cuadro un año antes de su ingreso al hospital con aumento de volumen en rodilla izquierda y dolor. Los estudios de imagen mostraron una tumoración heterogénea yuxtacortical localizada en la superficie posterior de la metáfisis femoral distal. Se realizó biopsia incisional, con diagnóstico de osteosarcoma parosteal y se realizó resección quirúrgica amplia. De acuerdo con los hallazgos de la pieza quirúrgica se realizó el diagnóstico de osteosarcoma parosteal con componentes de condrosarcoma y liposarcoma de bajo grado. El conocimiento de esta rara variante de osteosarcoma parosteal puede llevar a los ortopedistas oncólogos a considerar otros componentes y proporcionar márgenes quirúrgicos adecuados. CONCLUSIÓN: presentamos las características clínicas, histológicas y de imagen de un osteosarcoma parosteal con componentes de liposarcoma y condrosarcoma de bajo grado.

Ochronotic arthropathy as a paradigm of metabolically induced degenerative joint disease. A case-based review.

Alkaptonuria is a rare, hereditary metabolic disorder in which a deficiency in the homogentisate 1,2-dioxygenase enzyme results in an accumulation of homogentisic acid. Deposition of excess homogentisic acid in different intra- and extra-articular structures with high content of connective tissue causes brownish-black pigmentation and weakening, ultimately resulting in tissue degeneration and finally osteoarthritis. Ochronotic arthropathy is considered a rapidly progressive, disabling condition in which weight-bearing joints and the thoracolumbar spine are predominantly affected. Patients often require multiple joint replacements, such as in the case of the patient presented here. At present, there is no definitive cure for ochronosis, and management is predominantly symptomatic.

[Pseudoseptic arthritis with foreign body synovitis in a patient with gout]. / Artritis seudoséptica presenta sinovitis por cuerpo extraño en un paciente con gota.

Monoarthritis is a diagnostic challenge for the clinician, as the list of associated conditions is quite long. It is accepted that in patients with a diagnosis of inflammatory joint disease monoarthritis represents exacerbation of the underlying disease. However, ignoring the systematized approach to monoarthritides may lead to omissions and mistaken diagnostic implications. This report describes the approach to a case of pseudoseptic arthritis that mimicked an acute episode of recurrent arthritis due to monosodium urate in a patient with retention of an intraarticular foreign body.