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MUSCULOSKELETAL RADIOLOGY Table of Contents   
Year : 2000  |  Volume : 10  |  Issue : 2  |  Page : 85-87
Psoriatic arthropathy: A pictorial essay


1 Radiologists, X-Ray Clinic, Opp. Commonwealth Building, Laxmi road, Pune 422030, India
2 Dermatologist, X-Ray Clinic, Opp. Commonwealth Building, Laxmi road, Pune 422030, India

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Keywords: Psoriasis, arthritis

How to cite this article:
Rahalkar M D, Bhave C M, Lonkar A Y. Psoriatic arthropathy: A pictorial essay. Indian J Radiol Imaging 2000;10:85-7

How to cite this URL:
Rahalkar M D, Bhave C M, Lonkar A Y. Psoriatic arthropathy: A pictorial essay. Indian J Radiol Imaging [serial online] 2000 [cited 2019 Nov 18];10:85-7. Available from: http://www.ijri.org/text.asp?2000/10/2/85/30608
It has been appreciated for more than a century that bone and joint changes are associated with psoriasis.

As early as in 1818, interest was focussed on this association, when Aliber first reported its occurrence. Through subsequent innumerable papers published later, this association has been firmly established.

Psoriasis is a disease of unknown etiology, characterized by the development of well-defined, erythematous, dry, scaly papules / plaques varying in severity and distribution. The lesion has a definable border; a bright red color and a silvery white scale and can occur anywhere. Three to five percent of all skin diseases in our country are due to psoriasis.

Psoriatic arthritis (PA) can be defined as an atypical arthritis with atypical psoriasis (particularly of nails) showing a reasonable amount of synchronous activity. The nail changes closely related to PA are: pitting of nail plate, yellowish discoloration, ridging, atrophy and hyperkeratosis. The concept of PA as a distinct entity has been endorsed by many, questioned by some and rejected by only a few. Storm in 1921 first reported an advanced case of PA. Subsequent reports described various forms of PA, such as 'distal arthritis', arthritis mutilans, rheumatoid arthritis (RA)- like and psoriatic sacro-Iliac (SI) arthritis / spondylitis.

Psoriasis can be associated with other diseases, particularly RA. Both are common and may coincide [1].

The association between ankylosing spondylitis and SI joint arthritis is well-known [2]. Non-marginal or marginal (described as teardrop or inverted comma-shaped) syndesmophytes were even described to be indicative of psoriatic spondylitis. Sundaram and Patton [3] reported para-vertebral ossification in 4 of 122 patients. However, these changes are now known to be non-specific.

Wright [4] observed nail involvement to be more common, when psoriasis was complicated by arthritis. Dermatologically, nail lesions can be in the form of pitting, onycholysis and subungual keratosis. However, results of other workers [5] seem to indicate that 10 % of patients develop arthritis before psoriatic lesions appear, 25 % develop simultaneous abnormalities and 65 % of patients show psoriasis before PA. Fitzpatrick [6] mentions that one in seven cases of PA have no evidence of psoriasis.

Radiographic Features of PA

Radiographs of hands and feet reveal three patterns of abnormalities [4],[7].

A) Distal Arthritis: The features are:

a) Predominant and simultaneous involvement of the DIP joints of the hands and feet, singly or associated with involvement of the PIP joints [Figure - 1],[Figure - 2],[Figure - 3],[Figure - 4]. Joint involvement in the form of:

a) Soft tissue swelling, more often asymmetric than not.

b) Juxta-articular erosions. These are largely subtle and found at the edges of the articular surface. In some cases, they are the only finding.

c) Narrowing of the joint space. This is less common. In contrast, in a few cases the joint space may look widened due to resorption of the phalanges.

d) No involvement of the PIP or metacarpo or metatarso - phalangeal joints is seen.

e) Peculiar involvement of the IP joint of the great toe is seen [Figure - 5]. Marked cartilage loss and sclerosis or new bone formation along the articular surfaces of the distal phalanges, are the notable features.

B. Rheumatoid arthritis - like lesions: These are less common but well documented. Erosion of the ulnar styloid process with adjacent soft tissue swelling and involvement of the PIP joints may mimic RA. However, the presence of psoriatic skin and nail lesions, absent rheumatoid factor and associated involvement of the DIP joints helps to make a confident diagnosis of PA [Figure - 6],[Figure - 7],[Figure - 8].

C. Arthritis mutilans -like changes have also been described [Figure - 9]. This patient had involvement of the DIP as well as PIP joints with marked resorption of the middle phalanx and flaring of its articular surfaces. Both joints were painless and could easily be 'telescoped' or pulled in and out; (described as ' opera-glass' hand). This is said to result when erosions of the articular ends of phalanges lead to gross destruction [4]. Coupled with a cup-like deformity of the proximal articular surface due to over-growth at tendinous insertions, a 'pencil-in-goblet' appearance results.

Other additional interesting findings can be:

1. Uniform lack of osteoporosis. This helps PA to be differentiated from RA.

2. Acrolysis (whittling).

3. Periosteal reaction along phalanges. Subtle periosteal reaction can be seen along the cortices of the middle phalanges of the toes or fingers. Moderate periosteal reaction along the cortices of the distal halves of the middle phalanges with sclerosis and expansion associated with fusiform soft tissue swelling, produces the well-documented appearance of a 'sausage digit' [Figure - 10],[Figure - 11] [5].

PA is a separate clinical, serological and radiological entity. It must be considered in the differential diagnosis of various conditions affecting the small joints of the hands and feet. Psoriasis of skin and nails, negative rheumatoid factor, involvement of the DIP joints of the fingers and toes (distal arthritis), involvement of the IP joints of the great toe, lack of involvement of the metacarpi and metatarso - phalangeal joints, absence of osteoporosis, occasional presence of mutilans - like destruction of phalanges and the 'sausage digit' appearance due to periosteal new bone formation, help in making a confident diagnosis of PA. Awareness of this entity can make the diagnostic radiologist an important link between physicians, rheumatologists and dermatologists.

 
   References Top

1.Baker M. Prevalence of psoriasis in polyarthritic patients and their relatives. Ann Rheum Dis 1965; 25: 229.   Back to cited text no. 1    
2.Lambert J.R, Wright V. Psoriatic spondylitis accompanying ulcerative colitis, regional enteritis, psoriasis and Reiter's syndrome. Arth and Rheum 1975; 14: 291-318   Back to cited text no. 2    
3.Sundaram M, Patton J. Para-vertebral ossification in psoriasis and Reiter's disease. BJR 1975; 48: 628.   Back to cited text no. 3    
4.Wright V. Psoriasis and arthritis. BJ Dermatology 1957; 69: 1.  Back to cited text no. 4    
5.Sutton, David. A Text-Book of Radiology and Imaging, 6 th Ed. Vol. 1. Chapter 4. Edinburgh: Churchill Livingstone, 1998: 96-97.  Back to cited text no. 5    
6.Fitzpatrick T.B, Eisen A.Z, Wolf K, Freeber I.M, Austen K.F. Dermatology in general medicine 5 th Ed. McGraw - Hill Publication, 1999; 530.   Back to cited text no. 6    
7.Moll JMH, Wright V. Psoriatic arthritis. Seminars Arthritis Rheum. 1973; 3: 55.  Back to cited text no. 7    

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Correspondence Address:
M D Rahalkar
X-Ray Clinic, Opp. Common wealth Building, Laxmi Road, Pune 422030
India
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10], [Figure - 11]



 

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