The Lamina Dura

The lamina dura is the bony lining of the socket (alveolus) of a tooth. The periodontal ligaments extend from the lamina dura to the cementum of the tooth, an keep the tooth in place. The lamina dura is cribriform plate produced by the periodontal ligament and fibers of the periodontal ligament are embedded within it.

While loss of the lamina dura (arrow in image above) is sometimes said to be pathognomonic for hyperparathyroidism, it can be seen in a wide range of conditions:

• Hyperparathyroidism: The case above is from a patient with primary hyperparathyroidism.
• Osteomalacia
• Osteoporosis
• Paget disease
• Leukemia
• Myelomatosis
• Cushing disease

The lamina dura can be thickened in bisphosphonate-related osteonecrosis of jaw (BRONJ)

References

• Arce K, Assael LA, Weissman JL, Markiewicz MR. Imaging findings in bisphosphonate-related osteonecrosis of jaws. J Oral Maxillofac Surg. 2009 May;67(5 Suppl):75-84.
• Berry HM Jr. The lore and the lure o' the lamina dura. Radiology. 1973 Dec;109(3):525-8.

Systemic Mastocytosis

Systemic mastocytosis (SM) refers to mast cell infiltration in extra-cutaneous tissues. The symptoms of systemic mastocytosis are due to degranulation of mast cells and/or accumulation of mast cells in target organs.

Degranulation of mast cells

Symptoms can be caused by secretion of the following factors:

• Histamine: Pruritus, urticaria, hypotension, gastric hypersecretion, bronchoconstriction.
• Heparin: Local anticoagulation, osteoporosis
• Leukotrienes: Bronchoconstriction
• Prostaglandins: Bronchoconstriction, flushing
• Platelet-activating factor:
• Proteases:
• Tumor necrosis factor:

Accumulation of mast cells in organs

Accumulation of mast cells in organs can cause organ dysfunction. The so-called B findings refer to organ involvement without organ dysfunction. C findings refer organ involvement with organ dysfunction. The example above shows hepatic involvement with cirrhosis (white arrow) and ascites (yellow arrow) and nodal involvement with bulky adenopathy (red arrow). We also have involvement with diffuse sclerosis. Interestingly, the non-radiology literature stresses the more common osteoporosis, with scarce mention of the sclerosis that tends to dominate the radiology literature.

Diagnosis systemic mastocytosis

The diagnosis of SM requires either, 1 major and 1 minor OR 3 minor criteria. Warning: Boring for radiologists

The one major criterion is: Multifocal, dense infiltrates of mast cells (≥15 mast cells in aggregates) in sections of bone marrow and/or other extra-cutaneous organ(s).

Minor criteria are:

• Bone marrow or other extra-cutaneous organs: >25% of mast cells in the infiltrate are spindle-shaped or have atypical morphology, or of all mast cells in bone marrow aspirate smears, >25% are immature or atypical.
• Activating point mutation at codon 816 of KIT in bone marrow, blood, or another extra-cutaneous organ.
• Mast cells in bone marrow, blood, or other extracutaneous organs express CD2 and/or CD25 in addition to normal mast cell markers.
• Serum total tryptase persistently > 20 mg/mL (unless associated w clonal myeloid disorder).

Subtypes

• Indolent (ISM): No C findings
• Smoldering (SSM): 2+ B findings, no C findings
• Aggressive (ASM): C findings, no MCL features*
• Mast cell leukemia (MCL): BMBx diffuse infiltration by atypical, immature mast cells. Aspirate smears ≥20% mast cells.
• SM with associated hematologic neoplasm (SM-AHN): SM + MDS, MPN, AML, lymphoma, other

References

Akin C, Gotlib J. Systemic mastocytosis: Determining the subtype of disease. UpToDate

The Cervical Split: A Pseudofracture

A horizontal line projecting over a cervical vertebral body on lateral radiographs can simulate a fracture or a butterfly vertebral body. This pseudofracture, the so-called cervical split, can result from the lucency between contiguous uncovertebral osteophytes, or, as in the case above, cervical scoliosis resulting in projection of the facet joint over the vertebral body.

A cervical split due to uncovertebral joint osteophyte formation is said to be always accompanied by disc space narrowing.

References

• Goldberg RP, Vine HS, Sacks BA, Ellison HP. The cervical split: a pseudofracture. Skeletal Radiol. 1982 Jan;7(4):267-72.
• Patinharayil G1, Han CW, Marthya A, Meethall KC, Surendran S, Rudrappa GH. Butterfly vertebra: an uncommon congenital spinal anomaly. Spine (Phila Pa 1976). 2008 Nov 15;33(24):E926-8.

Chronic Subperiosteal Iliac Hematoma

Subperiosteal iliac hematoma is caused by traumatic avulsion of the periosteum in children and young adults. The loose attachment of periosteum in young patients allows it to be displaced by hematoma in trauma. In the chronic phase, it is typically incidentally discovered by radiologists.

In the chronic phase, it presents as a lens-shaped ossified process on the internal aspect of the iliac wing with a ghost cortex (dotted line in the image above). It may or may not have the well-defined central lesion we have in this case.

References

Guillin R, Moser T, Koob M, Khoury V, Chapuis M, Ropars M, Cardinal E. Subperiosteal hematoma of the iliac bone: imaging features of acute and chronic stages with emphasis on pathophysiology. Skeletal Radiol. 2012 Jun;41(6):667-75.