Solitary mastocytoma usually presents as an indurated,
erythematous, round or oval, yellow-brown or reddish-brown,
papule, plaque, or
nodule, typically measuring 1 to 5 cm in diameter. The lesion frequently has a leathery or rubbery nature and a
peau d'orange (pebbly, orange peel-like) appearance. The margins of the lesions may be sharp or vague. The degree of
pruritus varies; a lesion may be mildly itchy or asymptomatic. It normally develops larger for a few months, then for a variable amount of time grows in accordance to the patients size before gradually shrinking. Usually, the soles and palms are unaffected. The lesion may urticate on its own initiative or, more frequently, in response to being stroked or rubbed. The lesion becomes itchy,
erythematous, or
edematous when touched or rubbed; this reaction is known as the
Darier sign. The phenomenon is regarded as pathognomonic since it is brought on by the release of
mast cell mediators in response to physical stimulus. The diagnosis of
mastocytosis is not ruled out in the absence of a positive
Darier sign because it is evoked in only around 50% and 90% of patients with solitary mastocytoma and other kinds of
cutaneous mastocytosis, respectively. Certain lesions may erupt in painful blisters. Patients with solitary cutaneous mastocytosis may also experience systemic symptoms, however they are far more common in those with
systemic mastocytosis. These symptoms include
flushing,
dyspnea,
hypotension,
nausea,
vomiting,
abdominal discomfort,
diarrhea, and
headaches. == Causes ==