It looked very much like dermatomyositis, but there were no signs of muscle weakness. What would be in your differential diagnosis?
As a pediatrician focusing on adolescent medicine, I almost took the dermatology path but realized that the cases I was seeing in a primary care practice were more challenging than the referral cases my dermatology colleagues were seeingâ¦ and more fun, too.
I have never claimed to be a dermatologistâ¦ just a pediatrician (with the gift of a photographic memory) who on my own and with a lot of assistance learned and maintained a more than fundamental knowledge of pediatric, adolescent, and some adult dermatology.
I am a lifelong student (just as you should be) and often refer to myself as a PGY 43 (this year) who enjoys sharing what I have learned with my primary care colleagues and believes that the learning process should be both informative and fun.
In a recent case, we had the satisfaction of making the diagnosis of dermatomyositis in a 7-year-old girl who presented with muscle weakness and an unusual rash.
A Very Weak Young Girl with a Rash
A 7-year-old boy with a recalcitrant rash appeared to have dermatomyositis. However, he did not have: fatigue or muscle weakness, difficulty swallowing, joint swelling.
With the mother's consent, we ordered basic laboratory work and I consulted with a rheumatology colleague.
Muscle biopsy, EMG, and MRI were not ordered. Lab studies ordered were: ESR, CBC with differential, SGOT, SGPT, LDH, CPK, rheumatoid factor, ANA, Anti Jo1 antibody, EKG
Note reddish-blue lichenified papules on his knuckles, some ulcerated; also note mild erythema around the cuticles. I was certain these were Gottron’s papules.
Laboratory values/results were all WNL thus not suggestive of dermatomyositis. But my rheumatology colleague had confirmed my suspicions.
What is the most likely diagnosis? Rheumatoid arthritis, discoid lupus, a vitamin deficiency, dermatomyositis with normal labs, none of these
Diagnosis: Amyopathic dermatomyositis.
Characterized by presence of dermatomyositis for â¥6 months in persons who have normal muscle enzymes, no clinically significant muscle weakness. Muscle involvement may be delayed for several years.
Multiple studies indicate that in children the prognosis is far from clear. In one large study of children followed for â¥18 years 19% developed malignancies before age 18 but majority never had anything more than cutaneous findings.
For the current patient we refer to rheumatology for further evaluation and maintain close contact for all other health matters. Tests now required: MRI studies of large muscle groups, EMG, muscle biopsies, repeat labs.
This case did not end as we would have liked. Parents refused further testing and the child was lost to follow up after returning to his native Philippines.
Myopathic dermatomyositis has been classified more recently as a subset called clinically amyopathic dermatomyositis (CAMD). A 2006 systematic review offers an excellent parsing of this
“missing link in the spectrum of idiopathic inflammatory myopathies.”
Many diseases present as a spectrum; we had to investigate what didn’t make sense in the face of pathognomonic skin findings. In primary care, we should always be ready to learn more.
We can save time and cost by being thorough in the beginning or by going back to basics when we reach an apparent dead end. It's good for our patients and good for our own job satisfaction.
Roll Up for the Medical Mystery Tour This slide show on a rash that didn't make sense is the first in a 4-part series by Dr Jonathan Schneider, a primary care physician with a special interest in dermatologic disease and a passion for turning over every stone in the pursuit of an elusive diagnosis. As Dr Schneider's medical mystery tour will highlight, sometimes going the extra mile takes you back to basics -- ie, a full, comprhehsive medical history and physical examination.To begin the case, advance to Slide 5.Read Dr Schneider's introductory bio to get a feel for his commitment to patient care; then, enjoy the ride.When you've complete this case, visit our large library of Dr Schneider's other intriguing cases.Â Â Resources (in alphabetical order) Albal MB, Esposol EA, Vista EGS.Â Amyopathic Dermatomyositis with Interstitial Lung Disease: A Rare Type of Dermatomyositis with Accelerated mortality rate. Rheumatol Curr Res 2013, S16. http://dx.doi.org/10.4172/2161-1149.S16-004 Â http://www.omicsonline.org/amyopathic-dermatomyositis-with-interstitial-lung-disease-rare-type-of-dermatomyositis-accelerated-mortality-rate-2161-1149.S16-004.pdfAmyopathic Dermatomyositis â Genetic and Rare Disease Information Center, National Institutes of Health. Â (updated 2013)Â https://rarediseases.info.nih.gov/diseases/9907/amyopathic-dermatomyositisBailey EE Fiorentino DF. Amyopathic Dermatomyositis: Definitions, Diagnosis, and Management. Â Curr Rheumatol Rep. 2014;16: 465. http://link.springer.com/article/10.1007/s11926-014-0465-0el-Azhary RA, Pakzad SY. Amyopathic dermatomyositis: Retrospective review of 37 cases. JAAD. 2002;46:560â565Galimberti F, Li Y, Fernandez AP. Clinically amyopathic dermatomyositis: clinical features, response to medications and malignancy-associated risk factors in a specific tertiary-care-centre cohort. Br J Dermatol. 2016;174:158-64. doi: 10.1111/bjd.14227. Epub 2015 Dec 1. https://www.ncbi.nlm.nih.gov/pubmed/26490490Gerami P , Schope JM, McDonald L, Walling HW, Sontheimer RD. A systematic review of adult-onset clinically amyopathic dermatomyositis (dermatomyositis sine myositis): A missing link within the spectrum of the idiopathic inflammatory myopathies. J Am Acad Dermatol 2006 Apr; 54:597-613. https://www.ncbi.nlm.nih.gov/pubmed/16546580?access_num=16546580&link_type=MED&dopt=Abstract (See also: Callen JP. What is clinically amyopathic dermatomyositis? Comment in: NEJM Journal Watch, May 23, 2006. http://www.jwatch.org/jd200605230000001/2006/05/23/what-clinically-amyopathic-dermatomyositis)Pietrosanti M, et al. Clinically Amyopathic Dermatomyositis: Case Report and Review of the Literature. Int Trends Immun.2013;1. Â http://researchpub.org/journal/iti/number/vol1-no3/vol1-no3-9.pdfSaoud B, Allali F, Hajjaj-Hassouni N. Amyopathic dermatomyositis. Joint Bone Spine. 2006;73:318-20 https://www.researchgate.net/publication/7512470_Amyopathic_dermatomyositisSultan SM, Isenberg DA. Re-classifying myositis 30 years on from Bohan and Peter. Rheumatology. 2010;49: 831-833. doi: 10.1093/rheumatology/kep355. http://rheumatology.oxfordjournals.org/content/49/5/831.full