Metatarsal Stress Fracture

Oblique radiographic view of the foot shows transverse fracture lines of the proximal diaphyses of the forth and fifth metatarsals (arrows). Note sclerotic bone ends, periosteal reaction and minimal widening of the fracture gaps (degree of sclerosis is more on the forth digit)

Facts

• Spontaneous fractures of normal bone that result from summation of stresses
• Most common lower-extremity stress fracture
• Originally termed "march fracture" (seen in military recruits). Now seen in ballet, football, gymnastics and basketball
• Most common site = shaft (at diaphysis or neck)
• Increased incidence in pes cavus and pes planus foot

Radiography

• Often negative in early phase. May see thickening of cortex and small periosteal reaction
• Later, a fracture line with sclerotic bone ends, periosteal reaction, widening of fracture gap will be shown. 
• Late phase, the bone ends involved are entirely sclerotic 

References:

Schepsis AA, Busconi BD. Sports Medicine, 2006.

Baxter DE, Porter DA, Schon L. Baxter's the Foot and Ankle in Sport, 2008. 

Colonic Lymphoma

Axial (top) and coronal-reformatted (bottom) CT images show partial circumferential wall thickening (arrows) of the descending colon (C). Note smooth margin and homogeneous enhancement of bowel wall thickening, and disproportionate lack of colonic narrowing despite a large lesion. 

Facts:

• Lymphoma accounts for 0.2% - 1.2% of all colon malignancies
• Most common form of GI tract lymphoma is non-Hodgkin lymphoma (NHL)
• Most common sites of GI tract lymphoma is stomach, followed by small bowel
• For colonic lymphoma, most common site is cecum
• Nonspecific clinical signs and symptoms
• Due to rarity, Rx is not standardized. Often, it is surgically resected then chemotherapy is given

CT patterns of GI tract lymphoma:

• Nodular thickening of bowel wall
• Discrete polyp (causing intussusception)
• Long, distensible infiltrative lesion with ill-defined, thick walls with aneurysmal dilatation of the lumen
• Large exoenteric mass extending into adjacent soft tissues

Features differentiating lymphoma from adenocarcinoma of GI tract

• Bulky lymphadenopathy (lymphoma more likely)
• Marked luminal dilatation of bowel segment that is involved (lymphoma more likely)

Our case: Colonic mucosa-associated lymphoid tissue (MALT) lymphoma in a 67-year-old man.

References:

Buckley JA, Fishman EK. CT evaluation of small bowel neoplasms: spectrum of disease. Radiographics 1998;18:379.

Bairey O, et al. Non-Hodgkin lymphomas of the colon. Hematol 2006;8:832.

Sellar Mass with Calcification

Sagittal images (upper left = CT, upper right = T2W MR, lower left = T1W MR, lower right = T1W post-contrast MR) of the pituitary region of an elderly individual show a large sellar/suprasellar mass with internal calcification (hyperdense on CT, signal loss on MR). The mass is mostly solid and reveals heterogeneous enhancement. Note ballooning of the sella.

Differential diagnosis of a calcified sellar mass:

• Craniopharyngioma (most likely)
• Pituitary adenoma (unlikely, 0.2% - 8% have calcification)
• Rathke's cleft cyst (rare disease)
• Chordoma (rare disease)

Associated findings that help DDx:

• Nodular appearance of calcification --> craniopharyngioma
• Calcifications in a cystic mass --> craniopharyngioma
• Curvilinear appearance of calcification --> pituitary adenoma or Rathke's cleft cyst
• Bone destruction --> chordoma

This is a rare case of sellar/suprasellar chondrosarcoma confirmed with histology. 

Reference:

Kasliwal MK, Sharma BS. A rare case of pituitary adenoma with calcification: a case report. Turkish Neurosurg 2008;18:232-235

Glezer A, et al. Rare sellar lesions. Endocrinol Metab Clin N Am 2008;37:195-211.