Familial Incomplete Hypertrophic Osteoarthropathy: A Rare Disorder

Abstract

Dear Editor, Hypertrophic osteoarthropathy is a condition in which there is abnormal proliferation of skin and soft tissue, particularly around the periosteal tissues. It is a very rare condition which is mainly described as two types, in which the common form is secondary hypertrophic osteoarthropathy caused by underlying disease and the rare primary idiopathic form. Here, we present a case of incomplete familial form of hypertrophic osteoarthropathy where a young male presented with multiple joint pains and Grade 4 clubbing and large patella. A 24-year-old male presented with multiple joint pains predominantly involving both knees, elbows, and shoulders. There was no history of any joint swelling or morning stiffness. There was no other history suggestive of connective tissue disorder. On examination, Grade 4 clubbing was present [Figure 1]. Systemic examination was unremarkable. Musculoskeletal (MSK) examination revealed a significantly large patella on both sides [Figure 1]. There were no signs of inflammation. On further probing, the patient gave a history of similar clubbing and joint pains for his sister, brother, and grandfather. His father also has similar complaints but with less severity (pedigree charting below mentioned) [Figure 2]. On investigations, blood counts and liver and kidney function tests were normal. C-reactive protein was negative. Thyroid profile was normal. To rule out acromegaly, growth hormone levels and magnetic resonance imaging brain were done which were normal. X-ray hands and both knees were done suggestive of periostosis. MSK ultrasonography of the knees was done suggestive of zigzag appearance of the patella [Figure 3]. A diagnosis of incomplete familial hypertrophic osteoarthropathy was made as there was no skin thickening and no coarse facial features and no other systems such as hematological or endocrine are involved. He was prescribed etoricoxib, and on follow-up, he was symptomatically better. Genetic testing was not done in our patient as he is not willing for that.Figure 1: Digital clubbing with large patellaFigure 2: Pedigree chart showing affected individuals in three generationsFigure 3: X-ray showing periosteal reaction involving the terminal phalanges, both bones of forearm, and long bones of lower limbs. USG image showing Zigzag appearance of the patella. USG: UltrasonographyPrimary or idiopathic form of hypertrophic osteoarthropathy is very rare and constitutes only 2%–3% of cases. It is inherited as autosomal dominant or recessive disorder, and it was thought to be caused by impaired metabolism of prostaglandin E2.[1] Pachydermoperiostosis is an another name given to this disorder due to the presence of coarse facial features with underlying thickening and furrowing of skin.[2] If both skin involvement and periosteal components are present then it is called complete form. The other two forms are incomplete with prominent periosteal with less skin involvement (like our case) and fruste form with more skin features and less periosteal features. The diagnostic criteria for PDP (pachydermo-periostosis) include major criteria and minor criteria. Major consists of pachyderma, periostosis, and finger clubbing and minor criteria includes hyperhidrosis, arthralgia, gastric ulcer, cutis verticis gyrata, blepharoptosis, joint effusion, edema, seborrhea, acne, and flushing.[3] Endocrine disorders like acromegaly, hypothyroidism, acropathy and other conditions like multifocal periostitis to be ruled out before labeling this condition. The other mimic of this condition is psoriatic onycho-pachydermo-periostitis except for the presence of psoriatic lesions.[4] Nonsteroidal anti-inflammatory drugs are the main stay of treatment as they act by blocking prostaglandin synthesis. They can have a good prognosis and normal life span.[5] Other treatment modalities available are corticosteroids, colchicine, or bisphosphonates.[6] Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.