![A 70-year-old man presented with anemia (hemoglobin, 7.2 g/dL), a neutrophilic leukocytosis (neutrophils, 54 × 109/L), and splenomegaly. The bone marrow showed 100% cellularity, with myeloid hyperplasia and grade 3 fibrosis (panels A-B; hematoxylin and eosin [A] and reticulin [B] stains; original magnification ×400). Myeloproliferative neoplasm mutations were negative. A triple-negative myelofibrosis was diagnosed and ruxolitinib was started. The splenomegaly decreased, but the patient became dependent upon blood transfusions. He was referred for allotransplant. At review, the biopsy showed 10% kappa monotypic plasma cells (panels C-D; kappa and lambda stain; original magnification ×100). Immunoglobulin G kappa (30 g/L) and kappa light chain (1.335 g/L) were found, but no bone lesions, hypercalcemia, or renal insufficiency. A neutrophilic leukemoid reaction caused by ectopic granulocyte colony-stimulating factor (G-CSF)–producing plasma cells was considered, given the high level of G-CSF (375 pg/mL). Such a leukemoid reaction has been described, but not with extensive fibrosis. Bortezomib/thalidomide/dexamethasone was started, but after the third cycle, the disease progressed. After 6 cycles of carfilzomib/cyclophosphamide/dexamethasone, the bone marrow was less cellular (50%-80%) with grade 1 fibrosis and 1% to 2% polytypical plasma cells (panels E-H; hematoxylin and eosin [E], reticulin [F], and kappa and lambda [G-H] stains; original magnification ×400 [E-F] and ×100 [G-H]). The G-CSF level was <8.08 pg/mL. / The patient was consolidated by high-dose melphalan and remains in remission with normal blood counts.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/133/18/10.1182_blood-2019-01-894006/3/m_blood894006f1.png?Expires=1761680571&Signature=bUPFlEWdjDAgx2iAKkY3P2uU5zA3BFzRF-K3VOylJVjKLIXba3kxsYn4R5VoPdDbY7px4HIbUOyWI3sqVxymc2-3S6lOrZ8NWTakqAroxTlgms2I7dYuvLN0gYP~A3CvrNgmOcUrZb34ZyE04ssQuelcYcjUMHgEQS49aF9ancz-riY3F3waJ9~c-gkDtYNXYSsUH3rOXu7EbEVyHENxI~7wwBIuR-DAdcm6T0BTN~lPoSZyeA~8YlZbqYCkD00SlMtFXTP3SwytlsJZgqVQCWJ6wrLbFNSsOa0BFYqFDNDXItoK3q3O0d2m57BTr32NjMFHG3ea-hc4bwrUyedTMw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A 70-year-old man presented with anemia (hemoglobin, 7.2 g/dL), a neutrophilic leukocytosis (neutrophils, 54 × 109/L), and splenomegaly. The bone marrow showed 100% cellularity, with myeloid hyperplasia and grade 3 fibrosis (panels A-B; hematoxylin and eosin [A] and reticulin [B] stains; original magnification ×400). Myeloproliferative neoplasm mutations were negative. A triple-negative myelofibrosis was diagnosed and ruxolitinib was started. The splenomegaly decreased, but the patient became dependent upon blood transfusions. He was referred for allotransplant. At review, the biopsy showed 10% kappa monotypic plasma cells (panels C-D; kappa and lambda stain; original magnification ×100). Immunoglobulin G kappa (30 g/L) and kappa light chain (1.335 g/L) were found, but no bone lesions, hypercalcemia, or renal insufficiency. A neutrophilic leukemoid reaction caused by ectopic granulocyte colony-stimulating factor (G-CSF)–producing plasma cells was considered, given the high level of G-CSF (375 pg/mL). Such a leukemoid reaction has been described, but not with extensive fibrosis. Bortezomib/thalidomide/dexamethasone was started, but after the third cycle, the disease progressed. After 6 cycles of carfilzomib/cyclophosphamide/dexamethasone, the bone marrow was less cellular (50%-80%) with grade 1 fibrosis and 1% to 2% polytypical plasma cells (panels E-H; hematoxylin and eosin [E], reticulin [F], and kappa and lambda [G-H] stains; original magnification ×400 [E-F] and ×100 [G-H]). The G-CSF level was <8.08 pg/mL.
The patient was consolidated by high-dose melphalan and remains in remission with normal blood counts.
![A 70-year-old man presented with anemia (hemoglobin, 7.2 g/dL), a neutrophilic leukocytosis (neutrophils, 54 × 109/L), and splenomegaly. The bone marrow showed 100% cellularity, with myeloid hyperplasia and grade 3 fibrosis (panels A-B; hematoxylin and eosin [A] and reticulin [B] stains; original magnification ×400). Myeloproliferative neoplasm mutations were negative. A triple-negative myelofibrosis was diagnosed and ruxolitinib was started. The splenomegaly decreased, but the patient became dependent upon blood transfusions. He was referred for allotransplant. At review, the biopsy showed 10% kappa monotypic plasma cells (panels C-D; kappa and lambda stain; original magnification ×100). Immunoglobulin G kappa (30 g/L) and kappa light chain (1.335 g/L) were found, but no bone lesions, hypercalcemia, or renal insufficiency. A neutrophilic leukemoid reaction caused by ectopic granulocyte colony-stimulating factor (G-CSF)–producing plasma cells was considered, given the high level of G-CSF (375 pg/mL). Such a leukemoid reaction has been described, but not with extensive fibrosis. Bortezomib/thalidomide/dexamethasone was started, but after the third cycle, the disease progressed. After 6 cycles of carfilzomib/cyclophosphamide/dexamethasone, the bone marrow was less cellular (50%-80%) with grade 1 fibrosis and 1% to 2% polytypical plasma cells (panels E-H; hematoxylin and eosin [E], reticulin [F], and kappa and lambda [G-H] stains; original magnification ×400 [E-F] and ×100 [G-H]). The G-CSF level was <8.08 pg/mL. / The patient was consolidated by high-dose melphalan and remains in remission with normal blood counts.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/133/18/10.1182_blood-2019-01-894006/3/m_blood894006f1.png?Expires=1761680571&Signature=bUPFlEWdjDAgx2iAKkY3P2uU5zA3BFzRF-K3VOylJVjKLIXba3kxsYn4R5VoPdDbY7px4HIbUOyWI3sqVxymc2-3S6lOrZ8NWTakqAroxTlgms2I7dYuvLN0gYP~A3CvrNgmOcUrZb34ZyE04ssQuelcYcjUMHgEQS49aF9ancz-riY3F3waJ9~c-gkDtYNXYSsUH3rOXu7EbEVyHENxI~7wwBIuR-DAdcm6T0BTN~lPoSZyeA~8YlZbqYCkD00SlMtFXTP3SwytlsJZgqVQCWJ6wrLbFNSsOa0BFYqFDNDXItoK3q3O0d2m57BTr32NjMFHG3ea-hc4bwrUyedTMw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A 70-year-old man presented with anemia (hemoglobin, 7.2 g/dL), a neutrophilic leukocytosis (neutrophils, 54 × 109/L), and splenomegaly. The bone marrow showed 100% cellularity, with myeloid hyperplasia and grade 3 fibrosis (panels A-B; hematoxylin and eosin [A] and reticulin [B] stains; original magnification ×400). Myeloproliferative neoplasm mutations were negative. A triple-negative myelofibrosis was diagnosed and ruxolitinib was started. The splenomegaly decreased, but the patient became dependent upon blood transfusions. He was referred for allotransplant. At review, the biopsy showed 10% kappa monotypic plasma cells (panels C-D; kappa and lambda stain; original magnification ×100). Immunoglobulin G kappa (30 g/L) and kappa light chain (1.335 g/L) were found, but no bone lesions, hypercalcemia, or renal insufficiency. A neutrophilic leukemoid reaction caused by ectopic granulocyte colony-stimulating factor (G-CSF)–producing plasma cells was considered, given the high level of G-CSF (375 pg/mL). Such a leukemoid reaction has been described, but not with extensive fibrosis. Bortezomib/thalidomide/dexamethasone was started, but after the third cycle, the disease progressed. After 6 cycles of carfilzomib/cyclophosphamide/dexamethasone, the bone marrow was less cellular (50%-80%) with grade 1 fibrosis and 1% to 2% polytypical plasma cells (panels E-H; hematoxylin and eosin [E], reticulin [F], and kappa and lambda [G-H] stains; original magnification ×400 [E-F] and ×100 [G-H]). The G-CSF level was <8.08 pg/mL.
The patient was consolidated by high-dose melphalan and remains in remission with normal blood counts.
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