Table 2.

Patterns of lymphomatous bone marrow

Pattern	Definition	Predominant subtypes
Focal, random	Discrete lesion evident on low magnification	SLL, MCL, SMZL
Focal, paratrabecular	Discrete lesion by molding of lymphoma infiltrate against bony trabeculae	FL, MCL
Intravacular, intrasinusoidal	Neoplastic cells localized to sinuses and small vessels	SMZBCL, HSTL
Interstitial, diffuse, and variably patchy	Neoplastic cells dispersed throughout medullary space	BL, LL, ALCL, ENKTL
Diffuse solid	Discrete areas of complete effacement of BM between 2 bony trabeculae	BL, PTCL-NOS, LL, SLL, LPL, MCL, FL, SMZL

SLL, small lymphocytic lymphoma; MCL, mantle cell lymphoma; SMZL, splenic marginal zone lymphoma; FL, follicular lymphoma; HSTL, hepatosplenic T cell lymphoma; BL, Burkitt lymphoma; LL, lymphoblastic lymphoma; ALCL, anaplastic large cell lymphoma; ENKTL, extranodal NK/T cell lymphoma; PTCL-NOS, peripheral T cell lymphoma, not otherwise specified; LPL, lymphoplasmacytic lymphoma.