Systemic mastocytosis refers to a heterogeneous group of clinical disorders characterized by excessive mast cell accumulation in one or multiple organs. Mastocytosis is now considered as a separate disease category in the 2016 WHO classification of myeloid neoplasm and acute leukemia. It is no longer considered as a subgroup of meyloproliferate neoplasms. The clinical presentation of mastocytosis is heterogeneous ranging from skin-limited disease (cutaneous mastocytosis) to a more aggressive form with extra cutaneous presentation (systemic mastocytosis) with or without skin involvement. We are presenting a case of systemic mastocytosis that aroused in a patient who carried diagnosis of CMML for almost 2 years. The worsening B symptoms along with worsening splenomegaly were the driving factor for further investigations including Bone Marrow biopsy which revealed the diagnosis. A 74 year old Caucasian male with past oncology history of Chronic myelomoncytic leukemia diagnosed after persistant monocytosis on complete blood count . Patient presented with gradual onset of low grade fever , weight loss and night sweating , CT abdomen showed hepatosplenomegaly. core biopsy of the liver showed portal and lobular infiltrate consistent with involvement by mastocytes and extra medullary hematopoiesis. The infiltrate was positive for CD117, CD33, CD68, myeloperoxidase and CD163. Patient had bone marrow biopsy which showed increased CD117 positive cells consistent with involvement by systemic mastocytosis. The core biopsy showed multifocal nodules of spindle cells with fibrosis which was morphologically consistent with abnormal mast cells. Immunohistochemistry for CD117 was strongly positive in the spindle cell nodules and scattered polygonal cell nodules. KIT D816V mutation was detected. Patient met criteria for diagnosis of systemic mastocytosis with presence of previous diagnosis of CMML and classified as Systemic mastocytosis with an associated hematologic neoplasm (SM-AHN). Due to patient multiple comorbiditeis , he was not a candidate for Allo HCT. In an attempt to control his disease , patient was started on dose reduced Dacogen, but his functional status continued to delined and eventually dacogen was discontinued and patient was placed on best supportive car Conclusion Systemic mastocytosis is a rare entity with heterogeneous clinical presentation, highly variable disease course and consequently survival rates.Though recent advances in understanding genetic and molecular basis of disease, bone marrow transplantation remains the only treatment with possible curative potential in patients with advanced form of mastocytosis though carrying substantial mortality risk .Further understanding of Kit mutation might be able to offer a highly effective medication with durable response in a fashion similar to the success story of gleevac with CML treatment .

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive, rare malignancy. Exact incidence is unknown due to lack of diagnostic criteria. Typically, it involves skin and bone marrow and less likely, lymph nodes and visceral organs. We present a 76 year old male who started having a lesion on the left side of his back that was progressively enlarging. He initially started on antibiotic and topical medications for more than a month which did not help. Punch biopsy of the lesion was consistent with blastic plasmacytoid dendritic cell neoplasm, positive for CD2, CD5, CD7, CD43, weak CD58,Tdt, bcl-6. Patient denies fever, chills, night sweats, weight loss, change in appetite. Physical exam revealed a purplish lesion raised in the left upper back with multiple satellite-like purple lesions throughout the back. Laboratory showed white cell count 3.2 K/uL, hemoglobin 13 g/dL, platelet 135 K/uL. Bone marrow biopsy shows immature blastic neoplasm involving 15% of the bone marrow. Cytogenetics showed normal karyotype. Flow cytometry shows an immature lymphoid population with expression of CD4, CD56, and CD 123, negative for FLT3, IDH1, IDH2, NPM1 mutations. Positron emission tomography (PET) scan showed skin thickening with minimal FDG uptake in left posterior skin soft tissue of the chest near the shoulder with no other abnormal focal uptake and splenomegaly. BPDCN is a rare aggressive malignancy that is more common in older populations. The origin is from type 2 dendritic cells. Typical presentations are skin lesions, cytopenia, lymphadenopathy, and splenomegaly. Some of the cytological features of BPDCN include cloudy sky (blue cytoplasm with clearer areas), pseudopods, and microvacuoles. Confirmation of diagnosis is with immunophenotyping. Workup after diagnosis include complete blood count, liver and renal function, hepatitis panel, peripheral blood smear, bone marrow evaluation, systemic imaging, cerebrospinal fluid cytology. Treatment of BPDCN is challenging in this era. Most patients respond to chemotherapy, although they relapse. Tegraxofusp is suggested for remission induction therapy following allogeneic hematopoietic cell transplantation. Median overall survival is about one year. Only patients who underwent hematopoietic stem cell transplant had prolonged survival. Myelemia, old age and altered general state have worse prognosis.