Madan Mohan Gupta, N.U. BAHRI, MD

A 35-year-old patient presented with complaint of gradually progressive, painless swelling in left parotid region for 8 months. No history of fever and laboratory examination, past and family history was unremarkable. On examination, there was a smooth well marginated nontender swelling in left parotid gland. No evidence of enlarged cervical lymph nodes was seen.

Further noncontrast CT scan was performed, which revealed well-defined, well-circumscribed smooth marginated solid cystic lesion in superficial and deep lobes of left parotid gland, predominantly in posteroinferior part of gland, medially the lesion extends into stylomandibular tunnel (Figure 1). On postcontrast CT, irregular nodular enhancement of solid part was noted and in close relation to left external carotid artery and IJV, and antero-inferiorly retromandibular vein was compressed by the lesion (Figure 2). On noncontrast MRI, T2WI showed heterogenous signal intensity, T1WI images showed isointense signal within lesion and coronal showed slight hyperintense signal (Figure 3). There was no evidence of any enlarged cervical or intraparotid lymph nodes.

On basis of unilateral solid cystic lesion in middle-aged patient with irregular nodular enhancement of solid part of lesion with isointense signal on T1 and slight hyperintense signal on STIR images suggestive of two differential diagnoses were:

1. Cystic pleomorphic adenoma (due to unilateral solid cystic parotid lesion in middle-aged patient, enhancing solid part and no adjacent intraparotid and cervical lymph nodes)
2. Warthin tumor (due to irregular nodular enhancing solid part with isointense signal on STIR MRI)

Further ultrasound guided FNAC was taken, aspirated material appeared chocolate brown. On smear examination, oncocytes and lymphocytes cells were seen (Figure 4). Patient was operated on and histopathology revealed cystic spaces lined by a bilayer of oncocytic cells and abundant lymphocytes in the sub epithelial stroma (Figure 5).

 Noncontrast CT (A, axial and B, coronal) images show well-defined, well-circumscribed smooth marginated solid cystic lesion (arrow) involving superficial and deep lobes of left parotid gland predominantly in posteroinferior part of gland, further medially the lesion extends into stylomandibular tunnel (small arrow).

 Postcontrast CT (A, C, axial and B, D, coronal) images show irregular nodular enhancement of solid part (small arrow) and the lesion lies in close relation with left external carotid artery and IJV (large arrow) and antero-inferiorly retromandibular vein was compressed by the lesion.

 On noncontrast MRI, T2WI axial (A) shows heterogenous signal intensity, T1WI axial (B) shows isointense and STIR images (C, axial and D, coronal) images show slightly hyperintense signal intensity within lesion. No evidence of any enlarged cervical or intraparotid lymph nodes.

 On USG guided FNAC, aspirated material appears chocolate brown. On smear examination, oncocytes and lymphocytes cells are seen.

 Histopathology shows cystic spaces lined by a bilayer of oncocytic cells and abundant lymphocytes in the sub epithelial stroma.

 A warthin tumor (or papillary cystadenoma lymphomatosum) is a benign sharply demarcated tumour of the parotid gland. It is bilateral in 10-15 percent of cases. They are the second most common benign parotid tumour (after pleomorphic adenoma) and are the most common bilateral or multifocal benign parotid tumour. It typically occurs in the elderly (6th decade). There is a recognized male predilection. Patients typically present with painless parotid swelling. It favors parotid tail region for its location. It has a greater tendency to undergo cystic change than any other salivary gland tumor. On ultrasound, it shows as a relatively well-defined, ovoid, hyper echoic mass with anechoic internal cystic areas. On CT, it can be often seen bilaterally and appear as a cystic lesion posteriorly within the parotid with a focal tumor nodule relatively well-defined cystic changes with no calcification. On MRI, T1WI show low to intermediate signal with cyst containing cholesterol components containing focal high signal and on T2WI heterogenous signal intensity, on STIR images, hyperintense signal intensity within lesion. On postcontrast CT or MRI, solid part shows enhancement. Differential diagnosis includes adenoma, benign (BLEL) in HIV, carcinoma, adenoid, parotid nodal metastasis and parotid non-Hodgkin lymphoma.


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Articles

Case History: 35-year-old patient with gradually progressive, painless swelling in left parotid region, unremarkable history.

Unilateral Warthin Tumor Mimics Cystic Pleomorphic Adenoma 

 A 45-year-old female presented with complaint of occasional headache for last three years. Family and past history were unremarkable. Neurological and systemic examinations were normal. Blood analysis was within normal limits and EEG did not show abnormal discharges.

. T2W axial (A) and sagittal (B) MRI image show well defined intermediate to high signal intensity lesion in quadrigeminal cistern on right side (large white arrow) abutting inferior coliculus. The lesion does not cause mass effect or obstruct hydrocephalous and normal corpus callosum (small white arrow) in sagittal image.

. T1W axial MRI image shows high signal intensity lesion in quadrigeminal cistern on right side (arrow) which follow fat signal.

. FLAIR coronal MRI images show high signal intensity lesion in quadrigeminal cistern (arrow).

. Diffusion weighted MRI image shows no restricted diffusion within lesion (arrow).

. T1W fat sat pre-contrast (A) axial MRI image shows hypointense signal, suggests suppression of fat signal of the lesion (arrow) and T1W fat sat post-contrast (B) axial image shows no enhancement within the lesion (arrow).

Patient was referred for MRI brain by neurophysician.MRI was performed using 1.5 Tesla Siemens Magnetom Essenga spin echo T2 weighted (T2WI), T1WI, fluid attenuation inversion recovery (FLAIR), diffusion weighted (DWI), pre-contrast T1W fat sat and post-contrast T1W fat sat with slice thickness 5 mm. On MRI, there was a lesion in quadrigeminal plate cistern on the right side which showed intermediate to high signal on T2WI (Figure 1), high signal onT1WI (Figure 2), FLAIR (Figure 3), no restriction on diffusion weighted imaging (Figure 4), low signal on pre-contrast T1 fat sat (Figure 5) and showed no enhancement on post-contrast T1W fat sat (Figure 6). Sagittal MR revealed a normal corpus callosum (Figure 7). The diagnosis lipoma in quadrigeminal plate cistern on right side was made. The patient was managed conservatively and the patient's headaches subsided with conservative management.

 Lipoma in quadrigeminal plate cistern on right side

 Intracranial lipomas (ICLs) are rare intracranial lesions. They represent a group of congenital malformations of the brain parenchyma, are located more frequently in the pericallosal cistern and associated with other parenchymal or brain vascular malformations in up to half of cases. Intracranial lipomas are slow growing benign congenital lesions accounting for 0.1-0.5 percent of all primary brain tumors and are usually detected as incidental findings.

 Intracranial lipomas are histologically benign lesions that are congenital hamartomatous malformations derived from the embryologic meninx primitiva. ICLs are usually an isolated finding, but, uncommonly, may be associated with other intracranial malformations such as callosal dysgenesis with pericallosal lipomas. Lipomas of the quadrigeminal plate are usually asymptomatic,

 but may cause significant symptoms of mass effect in about 20 percent of patients.

 Pressure on the ventricular system can result in consequent neurologic deficits, obstructive hydrocephalus or raised intracranial pressure.

 Radiological characteristics of quadrigeminal cistern lipoma is always definitive on imaging, hence histopathological confirmation is almost never required.

 On CT scan, the lipoma is characterized by attenuation values of fat density (-50 to -100 Hounsfield units) and absence of post-contrast enhancement.

 On MRI, the lipoma has short T1 and T2 and therefore, a hyperintense signal is present on T1-weighted images and a relatively low to moderate intensity signal on T2-weighted images. The differential diagnoses of lipomas in the quadrigeminal cistern include: arachnoid cysts, tectal plate cyst, tectal masses (gliomas), supracerebellar abscess, dermoid and epidermoid cysts, ruptured P4 segment aneurysm of the posterior cerebral artery and, rarely, pineal region mass.

 The lipoma can be differentiated with other negative attenuation value lesions (epidermoid or dermoid tumors) that two tumors will demonstrate heterogeneous attenuation values.8 Intracranial lipomas rarely become symptomatic and surgery is seldom required. The usual neurological symptoms are intracranial hypertension and hydrocephalus, which can be treated by shunt procedure.

 Incidental and asymptomatic lipoma of the quadrigeminal region do not require surgical intervention,

 as our patient also presented with headaches but it appeared to be unrelated to the lipoma, as no compressive, obstructive or evidence of raised intracranial pressure were seen, hence the patient was managed conservatively.


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Case History: 45-year-old female with complaint of occasional headache for three years, had normal neurological and systemic exams.

Quadrigeminal Plate Cistern Lipoma 

 A 75-year-old patient presented with complaints of abdominal distension, generalized abdominal pain and breathlessness upon lying down position for six months. His liver function and renal function tests were within normal limit. Patient was sent for ultrasound examination, USG revealed thickened echogenic peritoneal masses predominantly in right iliac fossa and gross ascites with echogenic particles which (unlike other forms of particulate ascites, such as haemoperitoneum or pus in the peritoneum) do not move. Further USG guided ascites tapping was performed, which showed goblet cells and mucinous ascites. Patient’s ascites was aspirated many times but it recurred multiple times. Further CECT abdomen was performed, which showed gross ascites with internal nonenhancing internal debris causing scalloping of solid viscera of abdomen, like liver and spleen and displacement of small bowel loops centrally and medially and compresses retroperitoneal structures. There was also an ill-defined peripherally enhancing structure noted in RIF, s/o ruptured mucocele of appendix.

. Ultrasound shows thickened echogenic peritoneal masses (large arrow) predominantly in right iliac fossa and gross ascites (small arrow) with echogenic particles.

. Unenhanced CT axial image gross ascites (large arrow),central displacement of small bowel loops (small arrow).

. Contrast enahanced CT axial image gross ascites with nonenhancing internal debris causing scalloping of solid viscera (large arrow), central displacement of small bowel loops and ill-defined peripherally enhancing structure (small arrow) is also noted in RIF, s/o ruptured mucocele of appendix.

 Pseudomyxoma peritonei also known as “jelly belly” refers to intraperitoneal accumulation of a gelatinous ascites secondary to rupture of a mucinous tumor. The most common cause is a ruptured mucinous tumor of the appendix/appendiceal mucocoele. Occasionally, mucinous tumors of the colon, rectum, stomach, pancreas and urachal tumors are implicated. There is some ongoing contention as to whether primary ovarian tumors are a frequent source in their own right, or whether in these cases, the appendix is the primary site and the ovarian lesion is metastatic. Diffuse collections of gelatinous material in the abdomen and pelvis and mucinous implants on the peritoneal surfaces are noted. Spectrums from more benign to more malignant findings are present. On imaging, ultrasound shows echogenic peritoneal masses or ascites with echogenic particles which (unlike other forms of particulate ascites such as haemoperitoneum or pus in the peritoneum) do not move and small bowel loops displaced medially, and it may show scalloping of the liver, spleen and, at times, other organs. On CECT low attenuation, often loculated fluid thoughout the peritoneum, omentum and mesentery scalloping of visceral surfaces, particularly the liver scattered (curvilinear or punctate) calcifications may be frequantly present tends to remain localized to peritoneal cavity.

Differential diagnosis must include peritoneal mucinous carcinomatosis; treatment is repeated surgical debulking to decrease abdominal pressure and remove mucinous material build-up; complications are mucus buildup, increased abdominal pressure, bowel obstruction, renal failure and death; prognosis is median survival of two years has been reported although newer treatments are improving survival.


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Case History: 75-year-old patient presented with complaints of six months of abdominal distension, generalized abdominal pain and breathlessness when lying down.

Madan Mohan Gupta, N.U. BAHRI, MD

Articles

Unilateral Warthin Tumor Mimics Cystic Pleomorphic Adenoma

Quadrigeminal Plate Cistern Lipoma

Pseudomyxoma Peritonnei