Primary cutaneous marginal zone lymphoma (PCMZL) is reported to primarily affect non-Hispanic Caucasian males over 50 years old. We present a case of a 16-year-old female with mast cell activation syndrome (MCAS) who developed PCMZL of the skin of both cheeks, left forearm and right arm. The patient was treated initially with intralesional steroids which successfully shrunk lesions on her face and left forearm. Rituximab and doxycycline were attempted but stopped due to severe allergic reactions and anaphylaxis. Ultimately, the remaining nodules on her right arm were surgically excised.