INTRODUCTION
A 53-year- old Caucasian female with nevoid basal cell
carcinoma syndrome (NBCCS) and a long-standing
history of multiple basal cell carcinomas (BCCs) was
referred to our practice after moving to the area. Initial examination
revealed numerous BCCs on her face, trunk, and
extremities. The patient's medications included doxycycline
100 mg daily for rosacea, a multivitamin, B vitamins, and
a calcium supplement. Of note, the patient discontinued a
GDC-0449 (vismodegib; hedgehog pathway inhibitor) trial 22
months before urticaria. The treatment approach was directed
at surgical clearance of the BCCs followed by the routine
use of methyl aminolevulinate (MAL) photodynamic therapy
(PDT) to minimize tumor burden and slow future development
of BCC. Over a 6-month period, the patient underwent 5 MALPDT
treatments with standard 3-hour incubation under occlusion,
followed by 15 minutes of exposure to red light on the
trunk, arms, and facial areas. On her fifth and last treatment,
the patient experienced an urticarial reaction at the site of
MAL application (Figure 1) during exposure to red light, which
resolved with an oral antihistamine.
DISCUSSION
Nevoid basal cell carcinoma syndrome, also known as Gorlin
syndrome, represents a wide range of multiorgan anomalies
caused by a mutation in the PTCH1 gene. It is a hereditary
condition of concern to dermatologists primarily because of a
predisposition to develop BCC.1 Because of the early onset and
large number of tumors expected over a lifetime, particular attention
is directed at early identification and treatment of BCCs
when they are as small as possible. A recent addition to the
armamentarium for dermatologists in the treatment of BCC is
the use of MAL-PDT.
Photodynamic therapy involves the use of light to activate a
photosensitizing agent concentrated in abnormal skin cells,
creating a reactive oxygen species, which in turn destroys those
cells. Methyl aminolevulinate is one such photosensitizing precursor
currently utilized in several countries for the treatment
of superficial and nodular BCC on the face and body.2 The use
of MAL-PDT as a preventive measure for BCC in the management
of NBCCS is an approach that is used in our office. For
the patient in our case report, the management included frequent
skin exams (every 1 to 2 months) for early identification
of tumors, followed by appropriate surgical intervention, such
as Mohs micrographic surgery or destructive modalities, and
topical preventive therapy using MAL-PDT.
Though an effective treatment modality for nodular and superficial
BCC, with reported 24-month clearance rates of 88% for all
body sites,3 78% in complex cases (recurrent or large lesions, or
H-zone lesions),4 and 92.2% for small superficial BCC,5 MAL-PDT
is not without side effects. Cases of allergic eczema have been
described.6 Moreover, in a study of healthy people, Brooke et
al7 reported significantly elevated dermal histamine levels following
aminolevulinic acid PDT in the skin of all patients and
successful blockade of histamine release with a selective H1-
receptor antagonist. In our case report, the patient developed
urticaria on the fifth MAL-PDT treatment, indicating that urticaria
following MAL-PDT may be initiated by an immunoglobulin
E-mediated mechanism with histamine release from mast cell
granules in the dermis. In a prospective, observational analysis
by Kaae et al,8 12 of 1,353 patients treated with MAL-PDT developed
urticaria immediately following treatment, which had not
been experienced during previous sessions. All patients experienced
a localized cutaneous reaction only, as was the case with
