![A 60-year-old man with myeloma treated with lenalidomide-bortezomib-dexamethasone (4 cycles) and carfilzomib-cyclophosphamide-dexamethasone (4 cycles) presented for a routine follow-up bone marrow scan. Flow cytometry revealed κ-restricted plasma cells consistent with the patient's history. However, sections (panels A-B; original magnification ×50 [A] and ×100 [B]; hematoxylin and eosin stain) showed sheets of spindle cells arranged in fascicles with a vague storiform or herringbone pattern. There was scant hematopoiesis, and typical plasma cells were unapparent. On smears, few areas showed loosely cohesive plasmacytoid cells with round nuclei (panel C; original magnification ×40; Wright-Giemsa stain). The majority of the cellularity was composed of cohesive spindle cell aggregates positive for CD138, CD38, MUM1, κ, mild to moderate reticulin fibrosis (panels D, E, F, G, H, respectively; original magnification ×40; immunohistochemistry stain), CD56, CD20 (subset), and immunoglobulin G (IgG), but negative for Oscar, S100, SOX10, CD68, CD21, CD23, CD3, BCL1, CD117, tryptase, IgA, IgM, and λ. Thus, we confirmed extensive involvement by plasma cell myeloma with spindled morphology. / Plasma cell myeloma with spindle cell morphology is a rare histologic variant that necessitates the exclusion of other spindle cell neoplasms that can occur in bone, such as systemic mastocytosis, metastatic carcinoma, melanoma, or sarcoma, with spindled morphology or histiocytic/dendritic neoplasms. The clinical significance or the cause of this morphologic change is not well characterized in current literature.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/132/10/10.1182_blood-2018-05-849596/4/m_blood849596f1.jpeg?Expires=1735249767&Signature=dVIvrW9oX6edWBRlvh7toBy1GT5iUsJv2Nfom9evwvWZnKUpOo6PZofa8zdOD8nnj58g52VZ71MR1yK6A1J0cxYhIPWMsfClfs2I7GGB7nNBaE2BOXm-y2ftyenL89G-1to7jaOLJh2CpJ81DV0nhjRXZnJgF9yUJhCpPbaj7dhPRFLNNCQoyWw0rYFyy6opYW87-uPjVvRqkshMwxJgFA2s34Yj0F68zpkX9jm5y-VxdEdElUOeS5rNVBNZ8bdIO30vaboVcl5eoJh-Usfa-p2d91Dr2S89urxN2I~8OfQQV21xllpd94SuznGxB35SvcXZ~QWc5yTHNsZwg2bTzQ__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A 60-year-old man with myeloma treated with lenalidomide-bortezomib-dexamethasone (4 cycles) and carfilzomib-cyclophosphamide-dexamethasone (4 cycles) presented for a routine follow-up bone marrow scan. Flow cytometry revealed κ-restricted plasma cells consistent with the patient's history. However, sections (panels A-B; original magnification ×50 [A] and ×100 [B]; hematoxylin and eosin stain) showed sheets of spindle cells arranged in fascicles with a vague storiform or herringbone pattern. There was scant hematopoiesis, and typical plasma cells were unapparent. On smears, few areas showed loosely cohesive plasmacytoid cells with round nuclei (panel C; original magnification ×40; Wright-Giemsa stain). The majority of the cellularity was composed of cohesive spindle cell aggregates positive for CD138, CD38, MUM1, κ, mild to moderate reticulin fibrosis (panels D, E, F, G, H, respectively; original magnification ×40; immunohistochemistry stain), CD56, CD20 (subset), and immunoglobulin G (IgG), but negative for Oscar, S100, SOX10, CD68, CD21, CD23, CD3, BCL1, CD117, tryptase, IgA, IgM, and λ. Thus, we confirmed extensive involvement by plasma cell myeloma with spindled morphology.
Plasma cell myeloma with spindle cell morphology is a rare histologic variant that necessitates the exclusion of other spindle cell neoplasms that can occur in bone, such as systemic mastocytosis, metastatic carcinoma, melanoma, or sarcoma, with spindled morphology or histiocytic/dendritic neoplasms. The clinical significance or the cause of this morphologic change is not well characterized in current literature.
A 60-year-old man with myeloma treated with lenalidomide-bortezomib-dexamethasone (4 cycles) and carfilzomib-cyclophosphamide-dexamethasone (4 cycles) presented for a routine follow-up bone marrow scan. Flow cytometry revealed κ-restricted plasma cells consistent with the patient's history. However, sections (panels A-B; original magnification ×50 [A] and ×100 [B]; hematoxylin and eosin stain) showed sheets of spindle cells arranged in fascicles with a vague storiform or herringbone pattern. There was scant hematopoiesis, and typical plasma cells were unapparent. On smears, few areas showed loosely cohesive plasmacytoid cells with round nuclei (panel C; original magnification ×40; Wright-Giemsa stain). The majority of the cellularity was composed of cohesive spindle cell aggregates positive for CD138, CD38, MUM1, κ, mild to moderate reticulin fibrosis (panels D, E, F, G, H, respectively; original magnification ×40; immunohistochemistry stain), CD56, CD20 (subset), and immunoglobulin G (IgG), but negative for Oscar, S100, SOX10, CD68, CD21, CD23, CD3, BCL1, CD117, tryptase, IgA, IgM, and λ. Thus, we confirmed extensive involvement by plasma cell myeloma with spindled morphology.
Plasma cell myeloma with spindle cell morphology is a rare histologic variant that necessitates the exclusion of other spindle cell neoplasms that can occur in bone, such as systemic mastocytosis, metastatic carcinoma, melanoma, or sarcoma, with spindled morphology or histiocytic/dendritic neoplasms. The clinical significance or the cause of this morphologic change is not well characterized in current literature.
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