To the Editor:
Complex regional pain syndrome (CRPS) is a neurologic condition characterized by chronic pain and sensory changes, including allodynia and hyperalgesia, that usually affect the extremities.1,2 The syndrome is defined by the International Association for the Study of Pain (IASP) as a condition that appears regionally after an injury, with a variety of symptoms that often exceed the expected clinical course both in magnitude and duration, causing impairment of motor function and variable progression.3
Although CRPS most often is described following minor peripheral trauma, other precipitating causes include surgery and vascular events.4 Additional features of the condition include autonomic dysfunction, edema, and trophic changes.1 Symptoms of CRPS traditionally present in 3 stages, with notable skin changes most often documented in stages II and III.2
Skin changes are a known manifestation of the syndrome, but reports in the dermatologic literature are scarce. Qureshi and Friedman5 identified only 23 articles in the dermatology literature since 1990 in which skin changes in CRPS were described. We present a patient with a diagnosis of CRPS who developed hyperpigmentation and sclerotic changes, including skin thickening, induration, and skin tightening.
A middle-aged Black woman presented to dermatology for evaluation of progressive hyperpigmentation, hyperhidrosis, and sclerotic changes to the skin. Approximately 3 years prior, the patient was given a diagnosis of CRPS of the hands and feet. Pain symptoms started approximately 3 years prior to the onset of symptoms. Symptoms started in the left hand and eventually spread to the right arm, left leg, and subsequently to the right leg. The first dermatologic change the patient noticed was tightening of the skin in the affected area that led to decreased mobility, which improved over time—partly on its own and partly with physical therapy.
A biopsy performed by an outside dermatologist at the initial presentation demonstrated sclerodermalike changes, which were treated with creams but without improvement. Scleroderma was later ruled out by the same dermatologist. Skin tightening improved over time, with complete resolution approximately 1 year after the onset of symptoms.
Upon presentation to our clinic, the patient reported continuing intermittent flares of CRPS; however, she said she was most concerned about diffuse hyperpigmentation, which spread to include the face, arms, abdomen, legs (Figure), and buttocks and persisted after skin tightening resolved.
A, Diffuse dark brown to black patches on the superior right leg, which can be distinguished from the normal baseline color on the inferior portion of the lower extremity. B, Diffuse dark brown to black patches on the left leg, which can be seen along the anterior knee, anteriomedial shin, and on the dorsal foot.
To treat the hyperpigmentation, a decision was made to first focus on a localized area. Facial hyperpigmentation was chosen because it was of greatest concern to the patient. She was instructed to use azelaic acid gel 15% in the morning, tretinoin cream 0.05% at night, and sunscreen daily. The patient had mild improvement in hyperpigmentation after a 4-month period but has been inconsistent in follow-up. She continues to have intermittent flares of CRPS, which may interfere with her response to treatment. In addition to the aforementioned regimen of azelaic acid gel and tretinoin, she has continued to work with a pain specialist to better control the neurologic symptoms and pain associated with her CRPS.