Teaching Case

The patient was a thirty-nine-year-old woman who manifested pain and tenderness in both knees since the age of thirty-three. A routinary laboratory analysis in another centre demonstrated type IV hyperlipidemia. She did not refer any other clinical symptoms. She had no history of suffering fractures.

The patient was a thirty-nine-year-old woman who manifested pain and tenderness in both knees since the age of thirty-three. A routinary laboratory analysis in another centre demonstrated type IV hyperlipidemia. She did not refer any other clinical symptoms. She had no history of suffering fractures. On admission, results of physical exam were normal showing movement of all extremities without any inflammatory signs, as increase in warmth or edema. Laboratory data demonstrated hypercalciuria of 841 mg/d and hyperphosphaturia of 1824 mg/d with serum calcium level and serum phosphorus concentration within normal limits. Lipid plasma levels were trygliceride concentration 525 mgr/dl, plasma total-cholesterol 204 mgr/dl and high-density lipoprotein-cholesterol (HDL-C) 24 mgr/dl. Lypidogram revealed beta 28.5%, prebeta 66.5% and alpha 5.0%. The rest of laboratory data did not show other significant findings. In the moment of her visit to hospital she only manifested pain in both knees without revealing neurological nor psychiatric symptoms. The younger brother of the patient suffers a non-drafted bone disease. Plain radiographs of knees were obtained. The study was completed with radiographs of hands, ankles, cranium and spinal column. Biopsy from the cystic lesions of the affected bone marrow was performed to obtain histopathological and radiological correlation.

Membranous lipodystrophy represents a rare disease manifested as progressive skeletal and neuropsychiatric symptoms. In the description of an autopsy case with unusual findings in the nervous and skeletal systems Nasu et al firstly named the term "membranous lipodystrophy" [1]. Similar findings were reported in Finland by Hakola, referred as "progressive dementia and lipomembranous polycystic osteodysplasia". The aetiology of this disease is unknown. Some hypotheses have been proposed such as a development anomaly of blood vessels of bone, a metabolic disorder affecting structural common to both bones and myelin sheaths (Sourander et al. 1981), abnormal lipid metabolism, neuroaxonal dystrophy [Amano et al. 1987] and disturbance of glycolipid or glycoprotein metabolism [2]. Hereditary factors are also suggested. The clinical signs and symptoms may be divided into three groups: skeletal, psychiatric and neurological [3]. Although patients refer tenderness and local pain in the joints as the most common skeletal symptoms, pathological fractures of long bones may be the main cause of their visit to hospital. Radiological exams reveal large symmetric transparent cyst-like lesions in the metaphyses of long bones, in metatarsal bones and in phalanxes. The ribs, cranium, pelvic bones and spinal column are rarely affected [4]. The cortex near the affected region may seem thin in some cases but periosteal reaction is quite infrequent. Some patients may reveal psychiatric symptoms as the initial clinical feature manifested as presenile dementia or as upheavals of the mood. The neurological symptoms consist of convulsions, ataxia, urinary incontinence and disturbance of consciousness and appear in the final stages of the disease. Some authors have also reported that peripheral neuropathy may be one of the cardinal features of membranous lipodystrophy. The diagnosis of membranous lipodystrophy should be based on three main features: clinical manifestations, radiological exams and histopathological findings. Characteristic patterns of the illness involve the peculiar membranous transformation of marrow adipose tissue of the bone and, are not seen in hemangioma or lipoma of bone, healing fractures, or traumatic fat necrosis [5]. Other adipose tissues throughout the body are also affected. The presence of neuropsychiatric manifestations allows differentiating membranous lipodystrophy from other similar diseases.