Macular Foot Rash in an Active Duty Marine

A 24-year-old male Marine Corps member presented with a 5-day history of a nonpruritic macular rash on the plantar and dorsal surfaces of his feet and gluteal cleft (Figure). He had been sleeping in a self-dug hole during military training in the desert near Yuma, AZ, 5 days prior to presentation. He denied any change in food, sanitation, or hygiene products. The patient was in a long-term monogamous relationship with no recent sick contacts and denied taking any medications. Vital signs and the physical exam were normal.

Figure. Nonpruritic macular rash on the plantar and dorsal surfaces of the foot.

Discussion

The patient was diagnosed with erythema multiforme (EM). This often recurrent inflammatory disease is caused by a myriad of factors including drugs, malignancy, and infectious agents (most notably HSV and mycoplasma)—but is idiopathic in up to 60% of cases.^1,2 In drug-related EM, the most common culprits include allopurinol, barbiturates, penicillin, phenytoin, phenylbutazone, and sulfonamides. Although EM can be generalized, distribution of the dermatitis is most often confined to the hands, feet, face, and genital region.¹ 

The characteristic rash is pleomorphic and has been described as target-appearing due to the pale center surrounded by a darker annulus.³ The evolution of the rash begins with macules, progressing to papules. and culminates in vesicles and bullae.¹ Diagnosis is made through clinical observation, but confirmation for atypical cases can be achieved through biopsy. Treatment of symptoms is appropriate in this self-limiting disease. 

Given the atypical distribution of the rash in this case, diagnosis was confirmed with a biopsy. The etiology is unknown, but most likely, inoculation by coccidioidomycosis—a known infectious predecessor for EM—occurred when the patient dug his sleeping hole. Typically, disseminated coccidioidomycosis presents with pulmonary symptoms, but can present with solely dermatologic signs.⁴

Differential diagnosis. Disseminated gonococcal infection may present with the classic triad of migratory arthritis, tenosynovitis, and dermatitis. Of the 3, migratory arthritis is the most common (up to 80% of cases).⁵ Dissemination most often occurs in 2 to 3 weeks and in fewer than 3% of those with primary infection.³ More than 60% present with dermatologic issues, which are commonly found on the palms and dorsal surfaces of the feet and may include the trunk.⁵ Cultures may be obtained for confirmation of diagnosis. This patient had an otherwise normal physical exam, making disseminated gonococcal infection an unlikely diagnosis.

Hand-foot-and-mouth disease, caused by coxsackievirus (an enterovirus), presents with lesions on the palms, soles, and buttocks. Dermatologic symptoms are accompanied by fever and malaise.³ The rash is vesiculopustular in nature and the disease is more common and more severe in children.^3,5 Approximately 90% of those presenting with this self-limiting disease will have dysphagia.⁵ Diagnosis is clinical, but a biopsy can be performed for confirmation. This patient’s age, lack of fever and malaise, and macular rash, rather than vesiculopustular rash, helped eliminate the diagnosis of hand-foot-and-mouth disease.

Syphilis, a sexually transmitted infection caused by the spirochete, Treponema pallidum, first presents as a localized infection in the form of a painless chancre on mucosal surfaces. If untreated, a generalized infection ensues with 25% showing clinical signs of secondary syphilis.⁵ Most commonly, 2 to 10 weeks after the chancre, a macular exanthema appears, followed by a maculopapular rash on the palms and soles.^1,5 Additional symptoms may include fever, headache, malaise, and generalized lymphadenopathy. Diagnosis is best made by RPR or VDRL due to their high sensitivity, with confirmation by FTA testing.⁵ This patient showed no signs of primary syphilis infection, and no symptoms of secondary syphilis infection other than a maculopapular rash.

Rocky Mountain spotted fever (RMSF) is a rickettsial tick-borne disease affecting those in endemic areas. The maculopapular rash may progress to a petechial rash that begins peripherally (wrists, ankles) and spreads centrally. Appearance on the palms and soles typically occurs after central spread.¹ Other symptoms may include fever, headache, and myalgias, which may be accompanied by nausea, vomiting, and abdominal pain.¹ Diagnosis is clinical, but an indirect immunofluorescence antibody assay may be performed 7 to 10 days after presentation, thus delaying treatment.⁵ This patient’s rash did not follow the pattern of RMSF and he showed no other symptoms, making it an unlikely diagnosis. 

Acknowledgments: We would like to thank Dr Margaret Ryan and Maria Devore from Naval Hospital Camp Pendleton for their guidance and editing.

Matthew Lomeli, MD,
Marine Corps Air Ground Combat Center, Twentynine Palms, CA

Cassondra Majestic, MD,
The Ohio State University College of Medicine, Columbus, OH

References:

1. Wolff K, Johnson RA, Fitzpatrick TB. Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology. 6th ed. New York, NY: McGraw-Hill Medical;2009.

2. Wetter DA, Davis MD. Recurrent erythema multiforme: Clinical characteristics, etiologic associations, and treatment in a series of 48 patients at Mayo Clinic, 2000 to 2007. J Am Acad Dermatol. 2010;62(1): 45-53.

3. Emond RTD, Welsby PD, Rowland HAK. Color Atlas of Infectious Diseases. 4th ed. London, United Kingdom: Mosby;2003. 

4. Galgiani JN, Ampel NM, Blair JE, et al. IDSA treatment guidelines for coccidioidomycosis. Clin Infect Dis. 2005;41:1217-23.

5. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. St. Louis: Mosby, Inc;2010.