Jesse Keiser Fitzpatrick, MD
and Jeffrey Kohlwes, MD, MPH
Department of Internal Medicine , University of California San Francisco, San Francisco, CA, USA;
Department of Internal Medicine, San Francisco
Veterans Affairs Medical Center, San Francisco, CA, USA.
KEY WORDS: dermatology; photosensitivity; phytophotodermatitis.
J Gen Intern Med 33(6):975
© Society of General Internal Medicine 2018
31-year-old man presented after 1 week of painless rash
on his left hand. Examination revealed three non-
blanching hyperpigmented macules with mild scaling (Fig. 1).
Based on patient history of mixing margaritas outdoors 2 days
prior to rash onset, he was diagnosed with phytophotodermatitis.
Phytophotodermatitis is a common non-immunologic cutaneous
reaction caused by topical exposure to furocoumarin compounds
in the presence of sunlight. Furocoumarins in limes, carrots,
celery, dill, fennel, figs, parsley, and parsnips sensitize epithelial
DNA to ultraviolet light.
Cutaneous reactions are limited to
contact areas and are often delayed by 36–72 h. Diagnosis is
challenging because of the ubiquity of photosensitizing agents
and the delayed onset. Involvement of skin in direct contact with
beverage glasses is common, as are Bdrip lines^ and even
secondary hand imprints, which have been misdiagnosed as
Asymptomatic hyperpigmentation is the most
common reaction, but exposure can lead to severe sunburn with
blistering, which may require treatment in burn units.
is symptomatic, with rash resolution in weeks, though hyperpig-
mentation can persist for months. Avoidance of topical
furocoumarins and protection of skin from over-exposure to
sunlight are preventive.
Corresponding Author: Jesse Keiser Fitzpatrick, MD; Department of
Internal Medicine University of California San Francisco, San
Francisco, CA, USA (e-mail: Jesse.email@example.com).
1. Lankerani L, Baron ED. Photosensitivity to exogenous agents. J Cutan
Med Surg. 2004;8:424–31.
2. Goskowicz MO, Friedlander SF, Eichenfield LF. Endemic "lime" disease:
phytophotodermatitis in San Diego County. Pediatrics. 1994;93:828–30.
3. Pomeranz MK, Karen JK. Images in clinical medicine.
Phytophotodermatitis and limes. N Engl J Med. 2007;357:e1.
Figure 1 Clinical image showing hyperpigmented macules with mild
scaling over patient’s left hand.
Received August 25, 2017
Revised October 25, 2017
Accepted January 11, 2018
Published online January 29, 2018