Secretory Calcifications

Calcifications frequently appear on mammograms and need to be classified as benign or malignant. One  benign pattern is that of secretory calcifications. These calcifications (red arrows above) are smooth, linear or rounded, and radiate towards the nipple (long axis pointed towards the nipple). A branching pattern may be seen. The calcifications may have a radiolucent center indicating the noncalcified ductal lumen. Secretory calcifications are often bilateral and symmetric in distribution. 

The blue arrows show a region of smaller, clustered calcifications which were found to be malignant.


REFERENCES
Sickles EA. Breast calcifications: mammographic evaluation. Radiology 1986;160;289-93.

Fibrosing Mediastinitis

Fibrosing mediastinitis (FM) is due to abnormal proliferation of collagen and fibrous tissue in the mediastinum. It can present either focally or diffusely with the latter type involving multiple mediastinal compartments. Causes are either idiopathic or secondary to granulomatous infection (Histoplasmosis in the United States). 

FM is the most common benign cause of SVC obstruction. Imaging findings include a hilar or mediastinal mass causing mediastinal widening. The right paratracheal region is the most common location for occurrence of a mass. Focal FM tends to have calcified masses whereas calcification is less common in diffuse FM. 

Differential considerations include:

• lymphoma
• bronchogenic carcinoma - usually older patient, doesn't calcify

REFERENCES
Rossi SE, McAdams HP, Rosado-de-Christenson ML, et al. Fibrosing mediastinitis. Radiographics 2001;21:737-57.

Dyke Davidoff Masson Syndrome

Dyke Davidoff Masson Syndrome (DDMS) is a neurodegenerative disorder likely due to cerebral injury in utero or early in life. The main finding is cerebral hemiatrophy. Associated findings include ipsilateral compensatory calvarial thickening, enlarged frontal sinus, elevation of the petrous ridge and sphenoid wing.

The above images are from a young boy who presented with a history of seizures. There is asymmetric atrophy of the left cerebral hemisphere. Bone window examination demonstrates enlargement of the left frontal sinus.


REFERENCES
Grossman RI, Yousem DM. Neuroradiology, the requisites. Mosby Inc. (2003)

Congenital Midline Nasofrontal Masses

Midline nasofrontal masses are due to faulty regression of the midface dural diverticulum during embryologic development. The differential diagnosis includes:

• Epidermoid and dermoid cysts
• dermoid  
• ectoderm + skin appendages
• usually midline and tend to occur at the glabella
• epidermoid
• ectoderm without skin appendages
• usually paramidine
• Nasal gliomas
• not a neoplasm
• cerebral heterotopia
• can be intranasal (lateral nasal wall, middle turbinate, nasal septum) or extranasal (usually at glabella, +/- overlying skin telangectasia)
• T1WI - isointense/hypointense to gray matter
• T2WI - hyperintense to gray matter
• Encephaloceles
• herniation of intracranial content through a skull defect with a persistent connection to the subarachnoid space
• high prevalence of associated intracranial abnormalities
• intracranial cysts, callosal agenesis, interhemispheric lipomas, facial clefts, schizencephaly
• usually isointense to gray matter on all MR sequences 
• may be hyperintense on T2WI due to gliosis

REFERENCES
Lowe LH, Booth TN, Joglar JM, et al. Midface anomalies in children. Radiographics 2000;20:907-22.

Gallstone Ileus

The above clip demonstrates multiple calculi and air within the gall bladder, dilatation of distal loops of small bowel with relative collapse of the large bowel, and a large gallstone in the distal ileum. Tracing the distal common bile duct reveals a biliary-enteric fistula.

Trapped Periosteum in Physeal Injuries

Physeal injuries are common in the pediatric population and are usually classified by the Salter Harris system. One of the complications of physeal fractures is trapped periosteum. This can render a fracture as irreducible which may result in premature physeal closure. Trapped periosteum is important to recognize on imaging because it requires open reduction to prevent growth disturbances. 

On radiographs and CT with mulitplanar reconstruction, peristent physeal widening > 3mm after closed reduction is suggestive of trapped periosteum. The MRI findings of trapped periosteum have not been adequately described in the literature. A few reports seem to concur that on proton density weighted fat-suppressed images trapped periosteum appears as a low signal band insinuating at the physis. 


REFERENCES
Barmada A, Gaynor T, Mubarak SJ. Premature physeal closure following distal tibia physeal fractures: a new radiographic predictor. J Pediatr Orthop 2003;23:733-9.
Whan A, Breidahl W, Janes G. MRI of trapped periosteum in a proximal tibial physeal injury of a pediatric patient. AJR Am J Roentgenol 2003;181:1397-9.

Subtalar Dislocation

The above images demonstrate a medial subtalar dislocation (the foot and calcaneus are medially displaced). The mechanism of this injury is usually due to a fall from a height or a severe twisting injury as in the basketball player above who landed on an inverted foot.

Prompt reduction of this injury is necessary because associated damage to the tibial nerve, and posterior tibial artery and veins may be present and long term sequelae of neurovascular injury should be avoided.


REFERENCES
Lawrence SJ and Singhal M. Open hindfoot injuries. J Am Acad Orthop Surg 2007;15(6):367-76.