Case Study A Rare Sphenoid Sinus Mass Biology Essay

Amyloidomas are tumours dwelling of localised sedimentations of amyloid, an indissoluble, fibrillar proteinaceous stuff [ 1 ] . There has, nevertheless been a dearth in descriptions of its imaging findings in caput and cervix [ 6 ] . In our current instance where patient has old history of nasopharygeal carcinoma, a distinguishment between tumour return and benign lesion like amyloidosis could be hard. In the literature, there have been fortunes where amyloidosis has been misinterpreted radiologically as chondrosarcoma [ 8 ] but no study has mentioned sing its distinguishing characteristics from a nasopharyngeal carcinoma. In this article we discuss the differences in imaging visual aspect of amyloidosis and nasopharygeal carcinoma and how imaging can to boot assist in turn uping the defect in the skull base that cause CSF rhinorrhea and pneumocephalus.

CASE REPORT

This 49 twelvemonth old gentleman foremost presented with nosebleed in November 1996, underwent endoscopic biopsy and was diagnosed with nasopharyngeal carcinoma.

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Subsequently he underwent radiotherapy a month subsequently. He was symptomless until 2002 when he developed symptoms of allergic coryza for which he was treated with antihistamines. His symptoms improved and he was placed on a 6 monthly follow up.The patient remained good until June 2006 when he developed cacosmia without nosebleed. CT scan and MRI were performed demoing a mass originating from sphenoid fistula with sidelong extension to affect the cavernous fistula, inferiorly to affect the nasopharynx and posteriorly to affect the clivus. This mass was iso to hypointense in signal features to muscle on T1 weighted images and hypointense on T2-weighted images ( Fig 1A ) . After IV disposal of contrast stuff, mild sweetening could be seen ( Fig 1B ) .

Biopsy of the lesion was complicated by CSF leak. Patient so developed febrilities with concern and was treated with endovenous antibiotics. He was so referred to our Centre for fix of the CSF leak.

A repetition CT scan and MRI in our Centre confirmed the presence of bony defect in the sphenoid fistula with CSF leak and pneumocephalus ( Fig 2 and 3 ) . Since this lesion did non hold the typical visual aspect of nasopharyngeal carcinoma as it has low signal strength on T2-weighted images with minimum contrast enhancement. , hence a biopsy was planned at the clip of surgical fix of the CSF leak. Intraoperatively the mass was seen in the left side of the sphenoid fistula with gangrene. Biopsy of the lesion was taken. The site of the CSF leak was noted and was packed with fat transplant from the venters. Patient was treated with endovenous antibiotics and the CSF leak resolved.Histology of the biopsy tissue showed few fragments of a preponderantly formless hyaline stuff, with infiltrated by little Numberss of chronic inflammatory cells ( Figure 4A ) .

In some countries, the fragments showed surface epithelial liner, composed of benign ciliated columniform epithelial tissue. Congo-red positiveness was demonstrated, with presence of green bifringence on cross polarized microscopy scrutiny ( Figure 4B ) The histopathology of the biopsy specimen was confirmed as amyloidosis. Patient was discharged on a 6 monthly follow up.Fig 1A. Coronal T2-weighted MR image through the sphenoid fistula demonstrates asomewhat hypointense lesion ( * ) affecting the sphenoid fistula and wideninginto the left cavernous fistulas ( long pointer ) . Fig 1B. Contrast-enhanced coronal T1-weightedimages demonstrate minimum sweetening of the lesion ( short pointers ) . Note the normalcavernous fistula on the right side ( long midst pointer )Fig 2.

Contrast-enhanced axial CT encephalon demonstrate pneumocephalus in the frontletRegion ( pointer ) and in the sidelong ventricle ( arrowhead ) following biopsy of the mass.Fig 3. Reconstructed mid-sagittal CT image showing a mass busying the sphenoidfistula ( * ) with devastation of the clivus ( short pointer ) and cadaverous defects in the skull base ( longpointers ) .

Fig 4A. Histology of the biopsy tissue showed a few fragments of preponderantly formlesshyaloid stuff, which are infiltrated by little Numberss of chronic inflammatory cells.Fig 4B. Congo-red positiveness was demonstrated, with presence of green bifringence on crosspolarized microscopy scrutiny.

Discussion

Amyloidosis is characterized by idiopathic extracellular accretion of amyloid in tissues.

If the deposition is extended, it may interfere with organ or tissue map and even take to decease. Amyloid is a additive, nonbranching, fibrillar proteinaceous stuff that is arranged in a extremely organized manner [ 1 ] . Amyloidosis is classified into primary amyloidosis, myeloma associated amyloid, localized amyloid, secondary amyloidosis, familial amyloidosis, doddering amyloidosis and dialysis associated amyloidosis [ 5,9 ] . In a big reappraisal, 70 % of the instances were primary, 19 % were localized, 4 % were familial and 3 % were secondary [ 10 ] . Secondary amyloidosis is associated with chronic inflammatory conditions such as arthritic arthritis, Crohn ‘s disease, inflammatory intestine disease and connective tissue upsets.

In the caput and cervix part the localised signifier is the most common type. Amyloidosis of the caput and cervix is a benign disease with slow patterned advance. It has been reported that the signal features of amyloid on MR images closely resemble those of skeletal musculus, the construction of starchlike being similar in many ways to the extremely organized multilayered, myofibrillar ultrastructure of skeletal musculus. This may be an of import differentiating point to distinguish amyloidosis from neoplasms [ 11 ] . Most tumors have a more unstable construction than that of amyloid and skeletal musculus and therefore be given to lighten up on T2-weighted images. Other studies of amyloidosis, focal or systemic, depict this loss of signal strength on T2-weighted images [ 4 ] . The exact mechanism underlying the signal hypointensity of amyloid on the long-TR images is complex and unsure.

Gean-Marton et al [ 4 ] suggested that the alone construction of amyloid, the _-pleated sheath plays a function in several ways. First, enhanced T2 decay may ensue from inactive or easy fluctuating internal magnetic Fieldss within next starchlike protons held in fixed places within the folded protein. These magnetic Fieldss generate local field inhomogeneities, doing the protons to precess at somewhat different frequences. The protons therefore lose stage coherency, cross magnetisation, and, accordingly, T2 signal strength. Second, rapid chemical exchange and spin-spin interactions may happen between the starchlike protein and next H2O molecules. In chemical exchange, an “ in-phase ” outside H2O proton is substituted for a “ dephased ” proton within the starchlike protein. In spin-spin interaction, energy from a encompassing H2O proton is exchanged with energy from a spin on the starchlike protein.

Unlike chemical exchange, no physical exchange of affair occurs in spin-spin interaction. In both instances, the exchange leads to loss of stage. Because dephased protons are non imageable, a loss of signal strength occurs.

Finally, the starchlike microenvironment is composed of a heterogenous micromagnetic mixture of collagen, calcification, and vass every bit good as the amyloid fibrils. The T2 hypointensity may ensue from differences in diamagnetic susceptibleness. Proton diffusion within the voxel across these intrinsic gradients during interecho clip causes their stages to distribute out, ensuing in an irreversible decrease in cross magnetisation.The low signal strength of the mass can therefore assist to distinguish amyloidoma from other tumours, such as nasopharyngeal carcinoma and chondrosarcomas, because the latter characteristically exhibit high signal strength on T2-weighted images. The enhancement form of amyloidosis demonstrate assorted response. Some writers demonstrate no sweetening in the amyloidosis, although peripheral sweetening form has besides been reported in certain instances.

There are few instances that showed enhancement form as in our instance [ 2-6 ] . Hence enhancement form is non a clear distinguishing characteristics to distinguish amyloidosis from other tumor.Diagnostic pneumocranium after transsphenoidal pituitary surgery is rare [ 7,8 ] . Potential complications include tenseness pneumocranium, neurologic disfunction with increased intracranial force per unit area and meningitis, of which can be fatal. Tension pneumocranium may be manifested clinically by reduced degree of consciousness, concern, ictuss, decreased ocular sharp-sightedness, ocular field defects, or papilledema. Treatments of pneumocranium include observation, contraceptive therapy with systemically administered antibiotics, interpolation of intracranial drains, and fix or wadding of the floor of the sella as was performed in our current instance.An of import hint to the diagnosing of amyloidoma is the low signal strength on T2-weighted images which distinguishes it from other lesions. This visual aspect should take to biopsy to avoid unneeded chemotherapy or radiation therapy.

A conservative attack to this lesion was later adopted for our patient. Long term result is by and large favourable if this status.

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