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A rash more than just skin deep

Joe R. Monroe, PA-C, MPAS

Joe Monroe practices in the dermatology department of the Warren Clinic, Tulsa, Oklahoma, is the department editor for Dermatology Digest, and is the founder and past president of the Society of Dermatology Physician Assistants. He has indicated no relationships to disclose relating to the content of this article.

CASE

A seemingly healthy 55-year-old woman experienced muscle weakness that grew progressively worse over a 6-month period. She also developed an asymptomatic rash on her face and the dorsa of her hands and arms. After both problems had continued for another month, the patient was prompted to visit her primary care provider (PCP), who ordered blood tests. CBC and chemistry screen results showed no abnormalities. The PCP prescribed an NSAID and a topical steroid cream, neither of which resolved the problems. The patient’s condition continued to worsen to the point where she became too weak to go to work. In desperation, and despite repeatedly being told that her skin problems could have no connection to her muscle weakness, the patient decided to pursue a dermatology referral.

The patient was found to be anxious, tearful, and too weak to climb onto the examination table without help. Her vital signs were within normal limits. The dorsa of her arms and hands were covered with a dense, papulosquamous rash that spared the interphalangeal skin of all 10 fingers but intensified over the cuticles (see Figure 1).

The patient had no personal or family history of any skin diseases. She had no history of cancer and claimed that she was up to date on screening tests including mammography, Pap smear, pelvic exam, and colonoscopy.

WHICH STATEMENT BEST APPLIES TO THIS PATIENT?

The rash indicates a dermatologic emergency.
The eponymical designation for the rash pattern on her hands is Gottron’s papules.
A logical next step is to obtain a serum creatinine kinase.
A careful search for an occult malignancy is in order.

DISCUSSION

The correct answer is all of the above. All of these statements apply to this patient’s condition. The most likely diagnosis is dermatomyositis (DM), a potentially serious condition of unknown origin in which skin and muscles are typically inflamed. Tests used to confirm the diagnosis are serum creatinine kinase, aldolase, and antinuclear antibody, as well as skin and muscle biopsies.

Given the likely diagnosis, a timely, complete workup is needed to rule out an occult malignancy. In adult patients, specific malignancies mirroring those found in the general population are known triggers of this condition. Speed is called for both in making the diagnosis and in ruling out a malignancy.

TREATMENT This is an ongoing case. Because laboratory and biopsy results were pending at the time, the patient was initially treated with prednisone, 80 mg/d for 1 week; then 60 mg/d until a follow-up examination was performed 2 weeks later. A pelvic mass was seen on ultrasound, and a biopsy by laparoscopic technique was scheduled. If she has an operable cancer, the DM will improve very quickly after resection.

A presumed diagnosis of DM is unusual but not rare. Muscle weakness by itself has a totally different differential. The rash without the muscle problems would demand considering contact dermatitis, atopic dermatitis, or even lupus. This case shows what makes dermatology so challenging: a diagnosis is seldom made if not entertained.