Ebook Differential diagnosis in ultrasound (2nd edition): Part 2

(BQ) Part 2 book Differential diagnosis in ultrasound presents the following contents: Peritoneal and mesenteric masses, scrotum, testis and epididymis, prostate, breast, musculoskeletal system, orbit, neonatal and infant brain, neonatal and infant spine, gynecology and obstetrics.

Peritoneal and Mesenteric Masses

11.1 ROUND SOLID MASSES IN MESENTERY

1 Metastasis

2 Lymphoma

3 Leiomyosarcoma

• Metastasis from colon and ovary Metastasis due to

intraperitoneal seedlings are seen in primary mucinoustumors of ovary, appendix, colon and breast

• Lymphoma: Lymphoma may present as a

endoexoenteric mass with a solid mass in themesentery and adjacent small bowel mass

• Leiomyosarcoma: Of small bowel is most commonly

seen in ileum The large extrinsic component of thelesion is seen as a well-defined solid mesenteric masswith areas of necrosis

• Mesenteritis: Various conditions like Crohn's,

Tuberculosis (Figs 11.1.1 and 11.1.2) trauma, surgeryand pancreatitis may cause inflammation andthickening of the mesentery which on US may appear

as a focal echopoor mass This may also be seen as apart of retroperitoneal fibrosis

Figs 11.1.1A and B: US scans show chronic tubercular

peritoneal collection in the pelvis

as an ill-defined component mass engulfing and encasingadjacent normal loops.

• Fibromatosis

• Chronic or retractile mesenteritis, fibrosingmesenteritis: Retractile mesenteritis also called aschronic fibrosing mesenteritis or mesenterichypodystrophy is a rare condition of unknown etiologycausing fibrofatty thickening of the small bowelmesentery On ultrasound it may be seen as anonspecific ill-defined (hypoechoic or heterogenous)lesion at the root of the mesentery extending till thebowel border

• Lipodystrophy

• Peritoneal mesothelioma

• Fibrotic reaction of carcinoid

• Desmoid tumors

Figs 11.2.1A and B: Ascites with multiple thick internal septae

seen in (A) pelvis and (B) hepatorenal pouch

Figs 11.2.2A and B: (A) Abdominal tuberculosis: Interloop

fluid between loops; (B) Abdominal tuberculosis: Multiple hypoechoic well-defined lesion seen in the mesentery suggestive of lymph nodes

A

B

Fig 11.2.3: Ascites outlining bowel loops

Fig 11.2.5: US scan shows septate collection in

perforation peritonitis

Fig 11.2.7: Enlarged mesenteric lymph nodes

acoustic enhancement—case of tubercular peritonitis

Fig 11.2.9: Tubercular peritonitis—thickened

omentum (in calipers)

collection in the peritoneal cavity with internal septae suggestive of loculated ascites

Figs 11.2.11A and B: US scans show mesenteric adenopathy in

a case of Koch's abdomen

11.3 LOCULATED CYSTIC PERITONEAL MASSES

i Mesenteric: Lymphangioma, mesenteric cyst,mesenteric hematoma

ii Pseudomyxoma peritonei

iii Intra-abdominal abscess

iv Lymphocele

v Meconium peritonitis

vi Peritoneal tuberculosis

vii Omental cyst

viii Cystic mesothelioma

ix Cystic spindle-shaped tumors

x Paracardiac pseudocyst

xi Intraperitoneal hydatid (Figs 11.3.1 and 11.3.2)

Fig 11.3.1: Two hydatid cysts in peritoneal cavity—lower one

shows daughter cyst

11.4 SOLID PERITONEAL LESIONS

1 Mesothelioma

2 Carcinomatosis

3 Pseudomyxoma peritonei

4 Leiomyomatosis peritoneal disseminate

Mesenteric Cyst (Figs 11.4.1 and 11.4.2)

1 Usually found in the root of the mesentery

2 Sonographically it appears as unilocular cystic lesion.That may be septated, rarely a fat fluid level may beseen When differentiation from solid peritoneal lesionsand mesenteric cystic teratoma becomes difficult

1 Desmoid tumors

2 Occurs most commonly in abdominal wall

3 Occurs in mesentery also

4 Mesenteric dermoids are hypoechoic masses with area

of mesenteric shadowing due to fibrous tissue.Mesenteric lymphangioma are multiseptated lesions,which can attain large size and change shape They haveminimal noneffect on the adjacent bowel and nodisplacement of the mesenteric vessels is seen

Intraperitoneal Abscess

These develop usually following surgery, bowelperforation, trauma, pancreatitis or in patients withdecreased immune response The majority develop in theupper and down and on the right side

A loculated fluid collection containing gas bubbles(echogenic foci with reverberation artifacts) is stronglysuggestive of an abcess Ultrasound may reveal this typicalappearance or it may be seen as an ovoid or irregularly-shaped collection with debris, debris-fluid level (Figs 11.4.3and 11.4.4) or septations A complex appearance with

Fig 11.4.1: Mesenteric cyst—a large cystic anechoic SOL

with thin wall seen displacing the bowel loops

suggestive of mesenteric cyst

solid and cystic components can also be seen Some abscessmay simulate as echogenic solid mass.

Lymphocele

Surgery or trauma causes disruption of lymphatic vesselsresulting in lymph collection They are most commonlyseen in pelvis or intraperitoneal recesses (Fig 11.4.5).They usually appear as anechoic collection of variablesize Large collections can cause significant pressuresymptoms Complicated lymphocele contains debris orseptae

Meconium Peritonitis

Antenatal bowel perforation spill meconium into theperitoneal cavity which incites a foreign body reactionresults in formation of a cystic or complex mass havingechogenic walls

Fig 11.4.4: Fluid-debris level seen inside a

collection in the pelvis

Intestinal stenosis/atresia and meconium ileus are thecommon causes.

Occurs most commonly in the abdominal wall, butalso in the mesentery Mesenteric dermoid tumors arehypoechoic masses with areas of acoustic shadowing due

to fibrotic tissue

Lymphoma

• Most common primary mesenteric malignancy

• Isolated enlarged lymph nodes measuring more than1.5 cm in diameter are seen around the celiac axis

• SMA and in the porta hepatis

• Is a sarcoma arising from the serous membrane

• Closely related to asbestos exposure

• Thickening of the omentum forming a omental mantle

or cake is evident on US This appearance is also seen

in tuberculosis or peritoneal carcinomatosis

• Minimal ascites

• Liver metastasis pleural plaques and effusion, smallnodules may be identified on peritoneal surface or inthe mesenteric fat

Cystic Mesothelioma

Very rare neoplasm of the peritoneum It has noassociation with asbestos exposure

Peritoneal tuberculosis may be caused by direct spread

of bowel tuberculosis or by hematogenous dissemination

of a lung lesion On sonography a loculated fluid collectionwith septae and debris may be seen Associated featuresare mesenteric lymphadenopathy, omental case, bowelthickening and ascites

Omental Cyst

On ultrasound this appears as a well-defined, rounded,anechoic lesion present close to the bowel wall Thisresembles a mesenteric cyst which is present in the root

of the mesentery

Pancreatic Pseudocyst (Figs 11.4.6A and B)

Pancreatic pseudocysts are collection of pancreatic fluidwith a high amylase content surrounded by a fibrosiswall These develop in 50 percent of patients 2 to 3 weeksafter an attack of acute pancreatitis On US they appear

as a well-defined, walled off anechoic collection mostcommonly seen in the lesser sac Few dependent debrismay be evident Septae and echoes develop within itfollowing infection Other features or complications ofpancreatitis may also be evident

Metastasis

Metastasis to the peritoneum and mesentery usually arisesdue to intraperitoneal readings from a variety of sourcesmost common being carcinoma of ovary and GIT andbreast

On U/S thickened sheet-like greater omentum(secondary to infiltration by metastasis cells) appear as

"omental mantle or cake" In the presence of ascites smallnodules attached to the peritoneal surface are seen clearly

Figs 11.4.6A and B: (A) Pseudocyst pancreas—a large multiloculated collection seen in lesser sac with evidence of debris in it; (B) A large pseudocyst seen in lesser sac posterior to left lobe of liver Another pseudocyst is seen adjacent to it with evidence of internal septae

B

A

Enlarged isolated mesenteric lymph nodes orconglomerated hypoechoic lymph node may be evidentmasses (Figs 11.4.7A and B).

Pseudomyxoma Peritonei (Figs 11.4.8A and B)

Characterized by mucinous peritoneal implants andgelatinous ascites

Most often caused by secondary metastasis from mucinproducing adenocarcinoma of ovary, appendix, colon andrectum Hypoechoic to strongly echogenic nodular massesdistributed throughout the peritoneal cavity Thesedeposits characteristically scalloping the adjacent liversurface

Leiomyomatosis peritonealis disseminated: This conditionoccurs in pregnant or women of childbearing age group.Disseminated solid benign leiomyoma are seen a solidperitoneal masses Ascites is usually not present

Figs 11.4.8A and B: Meconium peritonitis in an infant—calcification

(arrows) on bowel wall surface with meconium filled peritoneal cavity

multiple mesenteric lymph nodes

Diffuse infiltrative lipomatosis: This rare disease entity affectsyoung people is characterized by overgrowth of fat in theretroperitoneum On US an echogenic mass is evidentwhich cannot be differentiated from liposarcoma.

Peritoneal Inclusion Cyst

• Also called multilocular peritoneal inclusion cyst orbenign cystic mesothelioma

• Uncommon benign primary peritoneal tumor that has

no relation with the malignant mesothelioma

• Occurs in premenopausal women with priorgynecological surgery or infection that results inperitoneal scarring The hormonally active ovariessecrete fluid that becomes loculated in the pelvis

• The imaging features are nonspecific except that ithas to be located in the pelvis:

– Multicystic pelvic mass

– Peritoneal surfaces of uterus, bladder

– May extend into upper abdomen

12 Scrotum

12.1 DIFFERENTIAL DIAGNOSIS

OF ACUTE SCROTUM Causes

1 Testicular torsion

2 Epididymitis with or without orchitis

3 Torsion of testicular appendages

9 Scrotal fat necrosis

10 Familial mediterranean fever

11 Abdominal pathology

Testicular Torsion

• Normal size and appearance early

• Hypoechoic after 4 to 6 hours due to edema

• Heterogenous after 24 hours due to hemorrhageinfarction known as missed torsion

• Hypoechoic epididymis

• Reactive hydrocele

• Skin thickening

• Enlarged twisted spermatic cord

Epididymitis with or without Orchitis

• The part affected is bulky, heterogenous andhypoechoic (Figs 12.1.2 to 12.1.4)

• Associated reactive hydrocele, skin-thickening

• Increased/normal color flow is the point ofdifferentiation from torsion (Figs 12.1.5 and 12.1.6)

• Infarction and abscess are the complications

Torsion of Testicular Appendage (Fig 12.1.7)

• Variable sized, ovoid to round, mobile hypoechoicmass with hyperechoic rim

• Decreased internal and increased external vascularity

sac showing hydrocele

Fig 12.1.2A: Epididymis is swollen with a collection adjacent to it

with internal echoes—epididymitis with scrotal abscess

lesion in Testis FNAC confirmed tubercular epididymo-orchitis

Testicular Trauma

• Pathologies that occur are hematoma, fracture, rupture

• A ruptured testes is ill-defined, hypoechoic,heterogenous with loss of normal contour and rupturedtunica Seminiferous tubules may be extruded

Fig 12.1.5: Power Doppler US scan shows vascular

extra-testicular mass

increased vascularity

• Fracture may or may not be seen as a hypoechoic line

• Hematoma is seen as a mass of variable appearanceaccording to age

Fig 12.1.7: US scan shows torsion of left testis

Idiopathic Scrotal Edema

• Between 5 to 11 year age

• Pain, swelling, erythema

• Thickened scrotal wall with normal testes andepididymis

• Increase/normal color flow in wall

• Especially in neonates with patent processus vaginalis

• Conditions that can cause secondary symptoms inscrotum are adrenal hemorrhage, delayed spleen

rupture of battered baby, hepatic laceration, Crohn'sdisease, acute appendicitis, appendix perforation

• Scrotal vein thrombosis due to catheterization offemoral vein during cardiac catheterization is anunusual cause

12.2 DIFFERENTIAL DIAGNOSIS OF SCROTAL

CALCIFICATION Testicular Calcifications

• Infective: Granuloma, tuberculosis (Figs 12.2.1 and12.2.2), filariasis, sarcoidosis

• Vascular: Infarcts, vascular malformation arterial wall

• Testicular microlithiasis

• Neoplasms: Burnt out germ cell tumor, large Sertolicell tumors, teratoma/teratocarcinoma gonado-blastoma (Figs 12.2.3 and 12.2.4)

Testicular Microlithiasis (Figs 12.2.5 and 12.2.6)

• Calcified specks within seminiferous tubules

• Corpora-amylacea-like bodies formed

• Associated with cryptorchidism, Klinefelter’s syndrome,tumors, pseudohermaphroditism

• Echogenic specks with comet tail artefact and noshadow

Fig 12.2.1: US scans show tubercular collection in scrotal sac

• Bilateral

• Follow-up 6 monthly with tumor marker evaluation

is a must

Fig 12.2.3: US scans show reversal of flow in varicocele

Fig 12.2.5: Testicular calcification (arrow)

• Lie between two layers of tunica with associatedhydrocele

• Consists of hydroxyapatite core with fibrinoid materialdeposited around it

Sarcoidosis

• Epididymal involvement more than testicular

• Recurrant painless inflammation, enlargement

12.3 DIFFERENTIAL DIAGNOSIS OF SCROTAL GAS

1 Infection by gas forming bacteria:

– Associated calcification, fluid, thickened wall/tunica

– Testes is bulky and hypoechoic

a Secondary: Metastasis, lymphoma, leukemia

b Primary:

– Malignant (Fig 12.4.1)

Germ Cell Tumors

More common in testis when it is in ectopic position(Figs 12.4.2 and 12.4.3)

90-95 percent mostly malignant

Fig 12.4.1: Testicular malignancy—right testis is replaced by a

solid mass of heterogeneous echotexture with few hypoechoic, anechoic and hyperechoic areas

echotexture SOL seen in the right inguinal region

Fig 12.4.2A(ii): The right scrotal sac is empty and left

testis is normal in position

biopsy from the lesion revealed seminoma testis

Fig 12.4.2B: Left ectopic testis lying in the inguinal canal

i Tumors of one histologic type:

ii Tumors of more than one histologic type:

• Teratocarcinoma (teratoma with embryonal cellcarcinoma)

• Any other combination

Gonadal Stromal Tumor

• 3-6 percent, mostly benign

• Leydig cell tumor

• Sertoli's cell tumor

• Granulosa cell tumor

• Theca cell tumor

• Tumors of primitive gonadal stroma

Fig 12.4.4A: Varicocele—multiple anechoic tubular channels

are seen in both the scrotal sacs

Fig 12.4.5: Gross hydrocele

in the left scrotal sac superior to testis in a case of left inguinal hernia

Fig 12.4.7: Fluid with thick septations in scrotal sac—pyocele

General Points

• Most extratesticular masses are benign whileintratesticular masses should be considered malignantunless proved otherwise

• Most benign lesions are uniformly echogenic while allechogenic lesions should not be considered benignblindly

• Most malignancies are hypoechoic to normal testesunless complicated by calcification, necrosis,hemorrhage and fatty change

Testis and Epididymis

13.1 DIFFERENTIAL DIAGNOSIS OF CYSTIC

TESTICULAR LESIONS Benign Cysts

a Simple cyst (Fig 13.1.1)

g Infaret (Figs 13.1.2A to C)

Malignant Cystic Lesions

a Teratocarcinoma

b Yolk sac tumor

c Hemorrhage and necrosis in any mass

d Tubular obstruction because of any tumor

e Lymphoma

Cysts in Testis are Discovered Incidentally in

8 to 10 percent of Population

Tunica Albuginea Cysts

• 2 to 5 mm, located on anterior/lateral aspect

• Simple cystic in nature

• Seen as multiple abnormal, tortuous channels in theregion of mediastinum showing no color flow

• Usually bilateral, may be associated with ipsilateralspermatocele formation

Cystic Dysplasia

• Congenital noncommunication between tubules andrete testes/efferent ductules

• Infant and young children

seen in the left testis