The lesions of PATM are symmetrically distributed on the bilateral legs and may be symptomatic in most cases, with severe pruritus being reported in several drug-induced PATM cases.3,5 Although the exact etiology of PPDs currently is unknown, some contributing factors that are thought to play a role include exercise, venous stasis, gravitational dependence, capillary fragility, hypertension, drugs, chemical exposure or ingestions, and contact allergy to dyes.3 Some of the drugs known to cause drug-induced PPDs fall into the class of sedatives, stimulants, antibiotics, cardiovascular drugs, vitamins, and nutritional supplements.3,6 Some medications that have been reported to cause PPDs include acetaminophen, aspirin, carbamazepine, diltiazem, furosemide, glipizide, hydralazine, infliximab, isotretinoin, lorazepam, minocycline, nitroglycerine, and sildenafil.3,7-15
Although the mechanism of drug-induced PPD is not completely understood, it is thought that the ingested substance leads to an immunologic response in the capillary endothelium, which results in a cell-mediated immune response causing vascular damage.3 The ingested substance may act as a hapten, stimulating antibody formation and immune-mediated injury, leading to the clinical presentation of nonblanching, symmetric, purpuric, telangiectatic, and atrophic patches at the site of injury.1,3
Levofloxacin is a broad-spectrum antibiotic that has activity against both gram-positive and gram-negative bacteria. It inhibits the enzymes DNA gyrase and topoisomerase IV, preventing bacteria from undergoing proper DNA synthesis.16 Our patient’s rash began shortly after a 2-week course of levofloxacin and faded within a few weeks of discontinuing the drug; the clinical presentation, time course, and histologic appearance of the lesions were consistent with the diagnosis of drug-induced PPD. Of note, solar capillaritis has been reported following a phototoxic reaction induced by levofloxacin.17 Our case differs in that our patient had annular lesions on both photoprotected and photoexposed skin.
The first-line interventions for the treatment of PPDs are nonpharmacologic, such as discontinuation of an offending drug or allergen or wearing supportive stockings if there are signs of venous stasis. Other interventions include the use of a medium- or high-potency topical corticosteroid once to twice daily to affected areas for 4 to 6 weeks.18 Some case series also have shown improvement with narrowband UVB treatment after 24 to 28 treatment sessions or with psoralen plus UVA phototherapy within 7 to 20 treatments.19,20 If the above measures are unsuccessful in resolving symptoms, other treatment alternatives may include pentoxifylline, griseofulvin, colchicine, cyclosporine, and methotrexate. The potential benefit of treatment must be weighed against the side-effect profile of these medications.2,21-24 Of note, oral rutoside (50 mg twice daily) and ascorbic acid (500 mg twice daily) were administered to 3 patients with chronic progressive pigmented purpura. At the end of the 4-week treatment period, complete clearance of skin lesions was seen in all patients with no adverse reactions noted.25
Despite these treatment options, PATM does not necessitate treatment given its benign course and often self-resolving nature.26 In cases of drug-induced PPD such as in our patient, discontinuation of the offending drug often may lead to resolution.
In summary, PATM is a PPD that has been associated with different etiologic factors. If PATM is suspected to be caused by a drug, discontinuation of the offending agent usually results in resolution of symptoms, as it did in our case with fading of lesions within a few weeks after the patient was no longer taking levofloxacin.