METASTASES

– Always consider in older patients
– Multiplicity and known primary

Imaging
Varies depending on tumor type and aggressiveness

– Lytic: Most tumor types
– Permeative: Highly cellular and small-round cell tumors (PNET, small cell lung, lymphoma)
– Sclerotic/mixed: Prostate, breast. Less frequently: Transitional cell, neuroendocrine, PNET
– Hypervascular: Renal cell, melanoma, thyroid, hepatocarcinoma, lung, neuroendocrine

Possible soft-tissue components

LYTIC AGGRESSIVE BONE LESION/S IN PATIENT >40 years old. METASTASES vs MYELOMA

MULTIPLE MYELOMA (MM)/SOLITARY PLASMOCYTOMA

– Affects older patients (median 68-70 years). Very rare under 40 years (<10%) Imaging
MM 4 patterns of bone involvement
– Diffuse lytic bone infiltration simulating osteopenia
– Multiple focal lytic well-defined lesions
– Solitary plasmacytoma
– Sclerotic bone lesions (exclusively associated with POEMS sd)

Solitary plasmacytoma in the skull: lytic, aggressive trans-diploic, soft tissues, and hypervascular aspect

LYMPHOMA

– 7% of all bone malignancy; 5% of extranodal lymphoma
– All ages; predominates in adults (peak 50-60 years); men/women 1.5:1
– Secondary dissemination >>> primary bone lymphoma
– Imaging characteristics of a hypercellular small round cell tumour

Imaging
– Trans-diploic permeative bone pattern and abundant of tissue components (small round blue cells spread through Haversian canals conditioning a striking relatively little bone destruction in comparison to important soft-tissue lesions)
– Hyperdensity on NECT, T2 hypodensity and striking diffusion restriction on DWI (all signs related to hypercellularity)
– Homogenous enhancement
– No or little necrosis

OSTEOSARCOMA

– Most common primary high-grade bone sarcoma
– Bimodal distribution: 10-14 and >40 years old
– Extremely rare in the skull in adults, and much more frequently arising from coexisting Paget’s disease> >previously irradiated bone> or bone infarction
– Clinically, quickly growing painful mass

Imaging
– Destructive, aggressive lesion, with periosteal reaction, soft tissue-mixed lytic-blastic component. May show “fluffy”, “cloud-like” osteoid matrix.

MENINGIOMA

– Most common brain tumor (36% of all brain tumors)
– Predilection for middle-aged females
– Can produce neurologic symptoms due to compression
– Most do not infiltrate bone, but when they do it, the hyperostosis is very specific, virtually pathognomonic
– Intra-diploic or trans-diploic meningiomas are less frequent

Imaging
Key signs:
– Calcifications
– “Dural tail” and extra-axial semiology
– Hyperostosis (very specific)
– Hypervascular with intense homogenous enhancement

*Even the great specificity of the hyperostosis, bone involvement can be VERY VARIABLE including aggressive-like lysis and periosteal reactions that do not exclude or go against the diagnostic

Ddx: Hemangiopericytoma (Solitary Fibrous Tumor New WHO 2016 classification). Younger, frequently male patients. Osteolysis possible, but NO hyperostosis. NO calcifications. The rest of imaging features identical to meningioma, differentiation is very difficult and challenging

EXAMPLES OF THE MULTIPLE FACES OF MENINGIOMAS AND THEIR BONE INVOLVEMENT. REMEMBER, POLYMORPHISM IS AN IMPORTANT FEATURE OF THIS ENTITY

With all the information mentioned above:

FINAL DIAGNOSIS: MENINGIOMA (WHO GRADE 2)

TAKE HOME MESSAGE REGARDING MENINGIOMA

– Very frequent, specially middle-aged women
– Important to know the classic characteristic features, some of them are very specific; but recognize the great polymorphism/many faces of this entity
– Advanced imaging can be helpful
– Not all the lesions in a neoplastic patient are metastases