A rare case of systemic mastocytosis (SM) associated with primary cutaneous follicle center lymphoma (PCFCL), a skin lymphoma, was recently reported in Annals of Hematology.
The case involved a 61-year-old woman who was initially diagnosed with bone marrow mastocytosisBone marrow mastocytosis A subtype of indolent SM that occurs when the excess mast cells accumulate in the bone marrow, but not the skin or other organs. (BMM), a variant of indolent SMIndolent SM A subtype of nonadvanced SM caused by the abnormal accumulation of mast cells in the bone marrow and other organs. Indolent SM accounts for around 90% of SM cases.. “Although similar rare SM cases with cutaneous lymphomas have been described our report is the first case of BMM-PCFCL,” noted the report’s authors.
Before diagnosis, the patient presented with systemic anaphylaxisAnaphylaxis A severe allergic reaction that can turn fatal without treatment. Patients with SM are at a higher risk of developing anaphylaxis. and mast cell activationMast cell activation Describes when mast cells release histamine and other mediators into the blood stream in response to an allergen or other trigger. This leads to symptoms like fatigue, rash and, in severe cases, anaphylaxis. symptoms, including urticaria (an allergic skin reaction) and hypotension (low blood pressure). Laboratory studies showed she had elevated tryptaseTryptase A protein enzyme that is primarily produced by mast cells and stored in small pockets within the cells, known as granules. High levels of tryptase are a key indicator of SM. and immunoglobulin E levels, but no sign of allergy.
A bone marrow biopsyBone marrow biopsy A procedure to collect a sample of bone marrow using a needle. Often used to examine the characteristics of mast cells and diagnose SM. revealed compact groupings of mast cellMast cell A type of white blood cell produced in the bone marrow. They help defend against infections and play a key role in allergic reactions. In SM, mast cells become overactive and build up throughout the body. that were positive for CD25, KIT and tryptase, and the D816V KIT mutation was identified in both her bone marrow and peripheral blood — all signs of SM. Since she didn’t show any signs of advanced systemic disease or additional hematologic neoplasms, she was diagnosed with BMM.
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Nine years after the initial BMM diagnosis, she developed red lesions on her scalp. A biopsy of these lesions revealed a dense dermal lymphoid infiltrate, which means that there was an abnormally high presence of lymphocytes (a type of white blood cell) in the second layer of the skin. The finding was consistent with PCFCL, which was confirmed by further testing. Her diagnosis was changed from BMM to SM with associated hematologic neoplasms (SM-AHN), an advanced form of SM.
AHNs are usually myeloid in nature, which means they involve cells in the bone marrow that normally make red blood cells, platelets and certain white blood cells (like neutrophils and monocytes). This case, however, was lymphoid in nature. Lymphoid neoplasms involve only lymphocytes, which are specialized immune cells that combat infection. The case is even more rare because it involved the skin: In most cases, lymphoid malignancies develop in the bone marrow.
The patient received local radiotherapy, resulting in complete resolution of skin lesions within three months.
“This unusual case demonstrates that patients with BMM may develop a lymphoid neoplasm in extramedullary sites, including skin,” the authors wrote.
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