Spot Diagnosis

Cyst (cystic air space)

CT
A round, parenchymal space with a well-defined wall; usually air-containing when in the lung but without associated pulmonary emphysema; commonly used to describe enlarged air spaces in end-stage fibrosis of interstitial lung diseases and also in Langheran's cell histiocytosis and lymphangiomyomatosis

Fig. 1 shows cysts of honeycombing, whereas Fig. 2 shows cysts of histiocytosis X

Brown tumors

Among other lesions that show giant cells, apart from giant cell reparative granulomas, are brown tumors. These occur in primary or secondary hyperparathyroidism and are usually the initial manifestation of these metabolic conditions.

The lesions present as osteolytic areas, sometimes with a ground-glass appearance, with relatively well-defined margins. No significant extra-osseous extension of soft tissue is seen. When solitary, differentiation from other entities is difficult, but if multiple, as in this 24-years old lady, it is possible to make this diagnosis prospectively. Sometimes there may be other findings as well, such as altered mineralization and periodontal bone loss.

Acute severe pancreatitis

In acute severe pancreatitis, there is more than one acute fluid collection and at least 30% or more necrosis, as seen in this case (Fig. 2 - arrow). Extensive peri-pancreatic fluid is seen (Figs. 1, 3). Necrosis is diagnosed as the absence of enhancement after at least 48 hours of onset of the inflammation. In the first 24 hours, the absence of enhancement may be due to ischemia and can lead to erroneous staging.

Transpedicular biopsy for central body tuberculosis

This 21 years old man had backache. The MRI showed a focal lesion involving the L3 vertebral body. The clinico-radiologic profile was suggestive of tuberculosis, but the orthopedic surgeon wanted to be sure.

The lesion (Fig. 1 arrow) was biopsied using a transpedicular approach. An 11G needle was introduced through the pedicle into the body (Figs. 2-4) and through it, an 18G gun was passed to obtain the biopsies (Figs. 5,6).

The diagnosis of tuberculosis was confirmed on the biopsy.

Head Injuries Lecture - Slides 33-34

Radiology grand rounds

Sumer has started the radiology grand rounds. Worth a look.

Chondroblastoma - femoral head

This was a 20-years old lady with a well-defined osteolytic lesion in the left femoral head (Fig. 1). Just as with the earlier examples in the tibia and humerus, this was a characteristic epiphyseal lesion. An MRI was performed, which showed a speckled appearance on the STIR (Fig. 2) and T2W (Fig. 3) images with intense enhancement and reactive synovial enhancement as well (Fig. 5).

In countries where tuberculosis is endemic, this may be considered as a differential diagnosis in the event of a less well-defined zone of transition and the presence of a significant amount of soft tissue or abscess formation.

PU junction injury - post-operative

The patient shown last week with a PU junction injury was operated. The urinoma was drained and a inferior calyceal-ureteric anastomosis was performed. A drainage tube was placed near the anastomosis, which kept draining significant urine for almost two weeks.

A repeat CT scan showed a leak at the calyco-ureteric junction (Figs. 1-4). Subsequently, this healed on its own and the patient is now fine.

Bronchiectasis

Pathology:
Irreversible dilatation of a bronchus or bronchi, often with thickening of the bronchial wall. Cylindric (tubular), saccular and cystic

Radiology:
Tubular or cystic, clustered spaces with or without air-fluid levels

Giant cell reparative granuloma

This 26-years old girl had a gradually increasing left cheek swelling. The CT showed an expansile lesion involving the left maxillary bone, effacing the sinus (Figs. 1-4). Marked thinning of the cortices was seen with heterogeneously enhancing soft tissue, without extra-osseous extension (Fig. 2). There was no osteoid or chondroid matrix. In the absence of signs of aggression, in the absence of an obvious "cystic lesion", this appearance is suggestive of, though not pathognomonic of a giant cell reparative granuloma.

GCRGs are proliferative fibroblastic lesions with multi-nucleated giant cells. It usually occurs in the 2nd decade in the jaw bones and is rare in the peripheral skeleton. It can be easily histologically differentiated from a typical giant cell tumor of the appendicular skeleton. This case is a typical example of a GCRG.