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it is caused by a defect in chromosome 19 and characterized by raised levels of low - density lipoprotein - cholesterol ( ldl - c ) (  bad cholesterol  ) that is passed down through families .
the condition begins at birth and can cause heart attacks at an early age . clinically
, fh is characterized by deposits of cholesterol in the vascular wall , causing atheromas , and extravascularly in the form of xanthomas , especially in the skin and tendons of patients with severe hyperlipidemia . here ,
two young sisters of age 6 and 4 years , born to a consanguineous marriage , presented to our dermatology clinic complaining of scattered , painless , and yellowish papules and nodules since birth progressively increasing in number and size . on examination ,
both children had intertriginous yellowish xanthomatous plaque in the gluteal cleft since birth ( 1  2 cm ) [ figure 1a ] and scattered yellowish xanthomas on both knees [ figures 1b and 2c ] and elbows [ figure 1c ] .
in addition , the younger sister had yellowish streaks of plane xanthoma on the side and back of the neck [ figure 2a ] , periumbilical xanthoma [ figure 2b ] and two subcutaneous soft swellings below the knees [ figure 2c ] .
ophthalmologic examination revealed lipid deposition in the cornea of both patients ( arcus juvenilis ) [ figures 1d and 2d ] .
older patient : multiple xanthomas ; intergluteal cleft ( a ) knees ( b ) elbows ( c ) and arcus juvenilis of corneae ( d ) .
inset : foamy xanthoma cells occupying the dermis ( h and e , 200 ) younger sister : multiple xanthomas ; sides and back of neck ( a ) periumbilical ( b ) knees with subcutaneous lipomatosis ( c ) and arcus juvenilis of corneae ( d ) lipid profile was done for patients , mother , and father , and it revealed elevated total and ldl - c levels with normal triglycerides and high - density lipoprotein - cholesterol ( hdl - c ) levels [ table 1 ] . blood sugar level , thyroid function tests , complete blood count , urine analysis , and liver and renal function tests were all normal , excluding secondary hypercholesterolemia .
hematoxylin and eosin - stained sections of the biopsied lesions revealed sheets and groups of foamy xanthoma cells with central nuclei occupying the whole dermis [ figure 1 inset ] .
lipid profile of patient , her younger sister , father , and mother echocardiography of both sisters and their parents revealed no abnormality .
ultrasound for tendo - achilles showed fusiform thickening with intrasubstance hypoechoic areas compatible with xanthoma .
ultrasound for the subcutaneous knee swellings revealed bilateral and symmetrical subcutaneous lipomatosis on the extensor aspect of both knees .
therefore , based on clinical , laboratory , and radiological findings , the diagnosis of homozygous fh was reached .
the whole family was advised to consume a diet low in cholesterol and saturated fat and rich in unsaturated fat in addition to lipid lowering drugs .
atorvastatin was prescribed for both patients ( 10 mg daily ) and their parents ( 20 mg daily ) .
after one month of treatment , the cholesterol level was reduced to 542 mg / dl in the older patient and to 500 mg / dl in the younger patient .
fh is clinically diagnosed by confirming the family history and characteristic findings such as cutaneous and tendon xanthomas .
cutaneous xanthomas may initially present in the intergluteal cleft or interdigital spaces on the dorsal surface of the hands and feet .
planar surfaces over the elbows and knees are the other common sites of appearance of xanthomas . of the affected individuals with fh , 75% complain of tendon xanthomas , usually located in the achilles or extensor tendons of the hands .
therefore , arthritis and tendinitis may attract attention to the diagnosis of patients with fh .
xanthomas develop because of lipid leakage from the vasculature into the surrounding tissues , where macrophages subsequently phagocytose these lipids . because cholesterol is not degraded , it accumulates within these cells , creating foamy macrophages .
the extracellular cholesterol crystallizes into the clefts , inducing an inflammatory reaction with giant cells and resultant fibrosis .
heterozygous fh is more common , with a reported prevalence of 1/500 and plasma ldl - c in the range of 297 - 425 mg / dl .
homozygous fh is rare , with a prevalence of 1/1,000,000 with plasma ldl - c of 444 - 1089 mg / dl .
our patients  the two young sisters  were diagnosed as having homozygous fh , since their serum cholesterol level was more than 600 mg / dl ; moreover , their parents have raised serum cholesterol level more than 200 mg / dl .
both cases had cutaneous intertriginous and tuberous xanthomas since birth , tendinous xanthomas with thickened achilles tendon , and arcus juvenilis of the cornea in the first decade of life , but fortunately , without cardiovascular complications yet .
this goes with other authors who set the diagnostic criteria of homozygous fh [ table 2 ] .
diagnostic criteria for homozygous fh from the literature effective fh screening by cholesterol testing should be done for all members of the extended family .
the treatment of fh consists of a diet low in total and saturated fats with a combined drug therapy .
effective drug combinations include low doses of bile acid sequestrants together with hmg - coa reductase inhibitors or niacin or all these agents combined .
a new third - generation statin , rosuvastatin demonstrated a significantly greater reduction in ldl - c as well as significantly greater increase in hdl - c compared to atorvastatin .
so , aggressive treatment including diet control , lipid lowering drugs , exercise , and control of risk factors will help reduce the morbidity and mortality associated with this disease .
follow - up is mandatory for monitoring treatment and early detection of cardiovascular complications and prompt treatment . to the best of our knowledge , the association between fh and symmetrical subcutaneous lipomatosis
was not reported before , and we present our case as the first report of this association . whether there is a genetic association between both conditions or
however , rubinstein et al . reported a family with familial combined hyperlipidemia wherein the affected members had nonsymmetric subcutaneous lipomatosis , and suggested the existence of a genetic linkage between the two characteristics .
moreover , they found a correlation between the degree of hyperlipidemia and the amount of these subcutaneous lipomas . 

we present our case as the first report of the association between homozygous fh and subcutaneous lipomas , which are interestingly symmetrically distributed.is there a relationship between the amount of these lipomas and the level of hyperlipidemia ?
we present our case as the first report of the association between homozygous fh and subcutaneous lipomas , which are interestingly symmetrically distributed .
is there a relationship between the amount of these lipomas and the level of hyperlipidemia ?
homozygous familial hypercholesterolemia is an autosomal dominant disorder of lipid metabolism , characterized by reduced clearance of low - density lipoprotein - cholesterol and a high risk of rapid development of cardiovascular diseases . 
 its incidence is relatively rare and estimated to be one in one million in general populations . here , 
 we report homozygous familial hypercholesterolemia in two egyptian young siblings , presented with cutaneous , tendinous xanthomas , and corneal arcus . one of them has symmetric subcutaneous lipomatosis , which has not been reported before in association with familial hypercholesterolemia .