Progressive right lower extremity enlargement

The patient and clinicians were concerned about the right lower extremity when in fact MRI showed the diseased extremity to be the left. The MR images (Figs. 1 and 2) show loss of subcutaneous fat throughout the left lower extremity with relative sparing of the muscle mass and medial thigh subcutaneous fat, accounting for the asymmetric size of the lower extremities and the misleading clinical appearance of an abnormally enlarged right lower extremity. The MRI distribution of subcutaneous fat loss of the left extremity was felt to be consistent with the diagnosis of lipodystrophy and in this patient attributed to adult onset dermatomyositis, which has been previously associated with lipodystrophy [1–3]. In addition, increased T2 signal on the STIR sequence within the subcutaneous tissues, particularly overlying the lateral left leg are indicative of active disease. Lipodystrophies are a group of disorders characterized by the loss of adipose tissue from various parts of the body, and have been categorized as being congenital or acquired and further subcategorized as generalized, partial, or localized [4]. The generalized varieties include congenital generalized lipodystrophy (Berardinelli–Seip syndrome) and acquired generalized lipodystrophy. Berardinelli–Seip syndrome is a rare autosomal recessive disorder in which there is a complete absence of adipose tissue at birth, while acquired generalized lipodystrophy manifests in late childhood and adolescence. Partial lipodystrophies include familial partial lipodystrophy (Dunnigan variety), which presents at onset of puberty, and acquired forms, which have been linked to HIV, drug use, and various autoimmune diseases. Localized forms of lipodystrophy are most often related to trauma, drug use, and autoimmune causes [4]. Patients affected by lipodystrophy are predisposed to insulin resistance. The central cause of morbidity and mortality in patients with lipodystrophy are diabetes mellitus and its long-term complications, including recurrent pancreatitis related to hypertriglyceridemia, chronic liver disease related to hepatic steatosis, and atherosclerotic disease [5]. Acquired lipodystrophies are the most common subtype, with HIV lipodystrophy accounting for over 100,000 cases of lipodystrophy in the United States alone [5]. The typical pattern of HIV lipodystrophy is loss of subcutaneous fat in the face and extremities, with compensatory circumferential adipose deposition in the submental (double chin), dorsocervical spine (buffalo hump), chest, and intra-abdominal regions [6]. This is in contradistinction to acquired partial lipodystrophy (Barraquer–Simons syndrome) and acquired generalized partial lipodystrophy. Acquired partial lipodystrophy is very rare (250 cases in the English literature), and characterized by subcutaneous adipose loss involving the face, neck, arms, chest, and abdomen, with compensatory circumferential adipose deposition in the thighs and lower legs [5]. Acquired generalized lipodystrophy (80 reported cases in the English literature) is characterized by circumThe case question and presentation can be found at doi:10.1007/ s00256-011-1271-7.