Subperiosteal hemorrhage in neurofibromatosis type 1

Neurofibromatosis type 1 (NF-1), in addition to a neuroectodermal disorder, is accompanied by mesodermal dysplasia that is accompanied by skeletal changes. The typical osseous findings include bowing of the legs, increase in length of long bones, pseudarthrosis, subperiosteal cyst formation, local bony erosions from adjacent lesions, and intramedullary neurofibromas. Except for the last two, which are due to direct involvement by neurofibromas, the remainder are due to dysplastic changes in bones.

A lesser known osseous presentation in bone is the propensity for subperiosteal hemorrhage and hematoma formation. The cause is unknown, but may be related to:

• Vascular abnormalities: For example, diffuse flat hemangiomas or plexiform dilated veins, which have been described in patients with hypertrophy of the extremities
• Dysplastic periosteum: The thinking is that mesodermal dysplasia manifests as an abnormally loose periosteum with poor callus response. This would predispose the patient to the formation and propagation of large subperiosteal hematomas.
• Direct involvement by neurofibromas: Subperiosteal infiltration by neurofibromatous tissues may loosen the periosteum and allow for massive hemorrhage following minor trauma.

References

• Herrera-Soto JA, Crawford AH, Loveless EA. Ossifying subperiosteal hematoma associated with neurofibromatosis type 1. Diagnostic hesitation: a case report and literature review. J Pediatr Orthop B. 2005 Jan;14(1):51-4.
• Steenbrugge F, Verstraete K, Poffyn B, Uyttendaele D, Verdonk R. Recurrent massive subperiosteal hematoma in a patient with neurofibromatosis. Eur Radiol. 2001;11(3):480-3.
• Yaghmai I, Tafazoli M. Massive subperiosteal hemorrhage in neurofibromatosis. Radiology. 1977 Feb;122(2):439-41.

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.

M.D. = Makes Decisions (unless you're a radiologist)

#
1	This is a cat.	This is a hemangioma.
2	This is most likely a cat.	This is most likely a hemangioma
3	This is consistent with a cat.	This is consistent with a hemangioma.
4	This is most likely a cat, but get a follow-up picture to make sure it wasn't a baby tiger all along.	This is most likely a hemangioma. Recommend follow-up to document stability.
5	This is most likely consistent with a cat.	This is most likely consistent with a hemangioma.
6	This is likely a cat, but can't exclude a tiger hiding behind it way in the distance.	This is likely a hemangioma, but can't exclude malignancy, sarcoid, etc.
7	This is likely a cat. Why don't you take a look for yourself and stop bothering me?	This is likely a hemangioma. Recommend clinical correlation.
8	This is likely a cat, but get a saliva sample and send it in for genetic analysis. Better yet, kill the cat and dissect it.	This is likely a hemangioma. Recommend biopsy. Open biopsy may be required.

In the real world (with the cat), anything other than statement #1 will get you laughed at. In radiology, statement #1 is rare. Instead we teach our residents and fellows, by our own weak examples, to be as non-declarative as possible.

Statements #2 and #3 are as declarative as most radiologists get. "I said most likely. What more do you want from me?!"

Statement #4 just passes the buck to the next radiologist.

Statement #5 combines 2 mild hedge words to produce one super-hedgy sentence.

Statement #6 is the reason Bayes rolls in his grave every time a radiologist signs a report.

Statement #7 is basically saying, "Thanks for the money suckers! This report was useless." We have access to so much patient data these days that it baffles me to see this in reports. Of course, this doesn't apply to cases where we're reading in isolation and when the only history we get from referrings is "pain," or some random ICD code. This negligent absence of data in a requisition borders on (is?) malpractice. I've seen it in imaging referrals my family members get from their doctors and it aggravates me to no end.

Statement #8, I don't even... For a cat/hemangioma?

Look, sometimes we have to hedge. Sometimes we are no better than Plato's cave captives, squinting at shadows with no idea of what's behind us. We know that two or more widely disparate entities can have identical imaging features. But when you know something can only be one thing, just say so. Save the patient some anxiety. And, save the rest of us some money by reducing unnecessary imaging.

What are some of your favorite radiology hedges?

Mimicker: Inguinal Mesh Plug

Left inguinal mesh plug with a lobular contour

Left inguinal mesh plug. Note conical morphology on this coronal MPR.

• Depending on the inguinal hernia repair method chosen, a mesh plug can be used for reinforcement. One such method uses a polypropylene (Prolene) plug
• The post-operative appearance of an inguinal mesh plug can masquerade as an inguinal mass or lymphadenopathy

Imaging Findings

• On CT, mesh plugs can have a slightly nodular or smooth outline. The density is similar to sightly lower than muscle. Mesh plugs have also been reported as a ring-like density with central fat attenuation, potentially mimicking epiploic appendicitis if on the left
• On MRI, mesh plugs are typically T1 hypointense and demonstrate variable T2 weighted signal
• Due to a granulomatous reaction, mesh plugs can be FDG avid

Helpful hints in preventing misdiagnosis

• Mutliplanar reformations can be useful in demonstrating the conical morphology of the mesh plug, although they can appear ovoid 
• Postsurgical changes including skin thickening and suceptabliity artifact can also be helpful imaging features

References

The British Journal of Radiology, 77 (2004), 261–265
J Comput Assist Tomagr. 2008Jul-Aug;32(4):529-32.
American Journal of Roentgenology. 2010;195: 701-706.