Discussion of the case
The middle-aged patient presented with a one-year history of polyarthritis of large and small joints and swelling in the lower limb, and infarcts of the right and left toe from the past 15 days. The patient was a driver by occupation, he was a non-smoker and had diabetes for the past 10 years with reasonable control. The patient’s history suggested an episode of neuropathy in the form of tingling and numbness in both lower limbs. He had a history of being admitted for behavioral abnormality and was out of medication. A physical examination of the patient revealed maculopapular rashes. A partial block of lower limb arteries on both sides was noted on Doppler evaluation. Clinical investigations revealed: increased inflammatory parameters, moderately elevated total count, negative APLA, ANA, and ANCA, and normal urine examination.
The possible differential diagnoses to be considered are inflammatory arthritis with vasculitis including primary vasculitis, connective tissue disease (CTD)- especially SLE or overlap CTD, and primary antiphospholipid syndrome. The other possibilities are diabetes, micro and macrovascular complications with additional inflammatory arthritis, and thrombotic condition overlapping with diabetic complications.
Since the patient had polyarthritis for the past year, the condition cannot be explained by diabetes alone. The presence of rashes and polyarthritis suggests a possibility of vasculitis. In addition, the presence of rashes and negative RF values suggest that the patient is less likely to have rheumatoid arthritis. The occurrence of digital ischemic infarct also supports the diagnosis of vasculitis, however, vasculitis is a late feature in RA. The Doppler finding of macrovascular disease and the negative ANCA, ANA, and APLA contradict the possibility of vasculitis.
The probability of overlap of inflammatory arthritis and macrovascular angiopathy of diabetic origin is more likely. Further evaluation including retinal examination, nerve conduction study, and skin biopsy, if possible, should be carried out. Soft tissue ultrasound is recommended to evaluate a possible infection at the site of infarction. However, the lack of pain in the infarct area suggested a possible association of neuropathy and diabetic microangiopathy as the probable cause of the infarct.
The eye examination suggested early proliferative retinopathy suggestive of micro and macrovascular complications. The presence of retinopathy supports the diagnosis of micro- and macrovascular complications of diabetes.
Polyarthritis involving small joints of hands and feet is reported to be one of the common musculoskeletal manifestations of diabetes.1Â The presence of polyarthralgia is a misleading feature in the present case. In addition, the co-occurrence of other possible autoimmune diseases was considered and evaluated. It is necessary to consider the alternative diagnosis in the presence of systemic features like polyarthritis, ulceration, or infarct, and in the absence of retinopathy.
Final Diagnosis
Diabetic macrovascular disease
Follow-up
The patient was followed up with diabetologist and plastic surgery team. The patient improved on regular diabetic foot care, and the inflammatory parameter receded by the next visit.
Learning point
In the presence of unusual features, it is preferable to evaluate alternative diagnoses.
Reference
1.Smith L, Burnet S, McNeil J. Musculoskeletal manifestations of diabetes mellitus. Br J Sports Med. 2003; 37(1): 30–35.
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