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SUMMARY Delayed exploration of an intrarenal “cystic” mass revealed an adenoma with malignant potentialities. It is suggested that “benign” solid tumour be considered routinely in the differential diagnosis of the renal mass.

Ultrasonographic examinations were carried out on four patients who had a total of six hydatid cysts. Three different patterns of cyst structure were recognized. These patterns are simple cyst, cyst with non-specific complex internal structure, and a “cyst within a cyst” pattern. The latter pattern depicting a daughter cyst within the primary cyst is thought to be a distinctive feature of echinococcal cysts, if not specific for them. Recognition of the cyst within a cyst pattern should permit a reasonably confident Ultrasonographic diagnosis of hydatid disease.

In 1951 Kirklin and co-workers 1 reported a study of 986 cases of parotid tumor seen at the Mayo Clinic from 1907 to 1944. They found that a little more than 300, or roughly one-third, of the patients had received previous surgical treatment for their parotid tumors by the time they entered the clinic. A previous operation had been performed on 33% of the patients with mixed tumor, 28% of the patients with Warthin's tumor, 28% of the patients with simple cyst, 52% of the patients with mucoepidermoid tumor, 53% of the patients with adenocarcinoma, 44% of the patients with cylindroma, 73% of the patients with undifferentiated carcinoma, 50% of the patients with undifferentiated sarcoma, and 54% of the patients with squamous-cell carcinoma. In other words, in roughly onethird of the patients with benign parotid tumor and in approximately one-half to two-thirds of the patients with malignant parotid tumor previous

✓ Four cases of simple cyst of the cerebellum treated at Stanford University Medical Center are presented. Review of the literature and past experience at Stanford suggest that they are uncommon. They seem to occur most often in middle age, presenting the signs and symptoms of an expanding cerebellar mass, and appear to be adequately treated by unroofing and draining the cyst cavity. It is suggested that these cysts do not have a congenital origin but rather represent a degenerated form of cerebellar astrocytoma.

We have reported a case in which there is evidence that a squamous-cell carcinoma has arisen in a pre-existing cyst. In view of the increasing number of similar case reports, it seems unwise to neglect the removal of any part of a cyst lining, especially in older patients.

1. Three solitary tumours of the peripheral nerve trunks are reported. None of the patients showed evidence of von Recklinghausen's disease. 2. The origin of these tumours is discussed; the evidence suggests that they develop from the Schwann cells of the nerve sheaths, and they should therefore be called neurilemmomas. 3. A solitary tumour of a peripheral nerve trunk is usually a neurilemmoma and not a neurofibroma. 4. These tumours are often mistaken for neurofibromas, from which they are wholly distinct. They are uncommon, but probably occur more often than is generally appreciated. 5. A neurilemmoma is a benign tumour which can be distinguished from a neurofibroma on clinical and operative grounds. It must be enucleated with preservation of its parent nerve. There is negligible risk of recurrence and no risk of malignant change after operation. 6. Neurilemmomas are liable to cystic degeneration, especially in situations where they are subjected to pressure or injury. This cystic change may later destroy the usual cellular structure of the tumour and convert it into a simple cyst.

A case is presented in which excessive injection of contrast material caused a simple cyst to appear as a hypovascular tumor.

Surgical techniques for thyroglossal cysts still vary considerably. In this review, one-third of patients treated by simple cyst excision had recurrence and this operation cannot be recommended. There should be consensus that excision of the mid-portion of the hyoid bone be performed routinely. However, variations have been described in the syprahyoid dissection. The present review indicated that the classic Sistrunk operation provided the lowest rate of recurrence and should remain the standard procedure.

A case is reported in which massive calycovenous reflux adjacent to an upper pole mass was demonstrated on a retrograde pyelogram. Pathologic examination revealed that the underlying lesion was a simple cyst.

Ameloblastoma of the jaw is a rare tumour which behaves differently from a simple cyst or tumour because it is locally invasive and tends to recur after removal. The pre-operative diagnosis is important as the removal of this tumour is a more extensive procedure than excision of a simple cyst or tumour of similar size. In this survey eleven of the sixteen presenting tumours showed as a radiolucent area with at least three of the following additional features: expansion of the overlying cortical plate; a corticated scalloped margin; a multilocular appearance; resorption of the root or roots of adjacent teeth. In these eleven cases the radiological features suggested the pathological diagnosis. In the other five presenting cases, a unilocular radiolucent area was present without additional features to suggest that the lesion was other than a simple cyst or tumour. All six recurrent tumours showed as a multilocular radiolucency with a corticated scalloped margin, and perforation of the overlying cortical plate was demonstrated in all of them.

A cadaver kidney, reported to contain a “simple cyst”, was received from another institution. Frozen section biopsy prior to transplant showed renal cell carcinoma. The contralateral kidney already had been transplanted at the other medical facility.

We discuss 5 children with simple renal cysts, 2 of whom were diagnosed initially as having a Wilms tumor or mesoblastic nephroma. The most common presenting feature of this lesion is a palpable mass, especially in the infant or younger child. In older children characteristic radiographic features can suggest a correct preoperative diagnosis. However, distinguishing a simple cyst and a solid tumor with necrotic degeneration may not be possible in the infant and younger child, and surgical exploration is indicated.

MR and CT features of neurocysticercosis are variable and depend fundametally on the stage in evolution of the infection, location, number and size of the worm. The authors retrospectively evaluated MR images obtained on a 2.0T superconducting unit in 22 neurocysticercosis patients and observed various MR features including some new findings. A variety of MR findings are presented with special reference to six case reports. The features include: (1) a large simple cyst containing both internal septations and a scolex; (2) suprasellar racemose cysts mimicking other cysts, (3) a fourth ventricular cyst readily depicted by aid of CSF flow-void in the sagittal plane; (4) degenerating cysts showing “white target” appearance; (5) granulomatous lesions having a “black target” appearance; and (6) a meningitic form showing Gd-DTPA enhancement of basal cisterns and of a subacute infarct.

The clinical value of the ultrasonic examination of renal masses is well established. Use of ultrasound scanning to distinguish renal cysts from solid tumors has been described by many authors 1–5 and is the most frequent use of renal sonography. Since most cystic lesions are benign and since solid masses large enough to be clinically apparent are often malignant, the usefulness of the technique has been to distinguish between these two general groups. The accuracy of differentiating between cystic and solid renal masses has been reported to range from 75–96% 3–7.

The use of living related donors for transplantation was first carried out in Boston and in Paris in the early 1950’s (1). Most of these transplants were between monozygotic twins and this procedure proved highly successful and the final results gave satisfaction to both donor and recipient as well as the whole family.

Ten cases of endometriosis presenting as pelvic masses are reviewed. Ultrasonically, these lesions were classified into three categories: cystic, mixed, and solid. In the cystic pattern, none had the smooth, well-defined wall and totally echo-free appearance characteristic of a simple cyst. Instead, the wall was shaggy and somewhat irregular with some evidence of septation. In the mixed type, the echographic appearance was compatible with pelvic inflammatory disease of an infectious etiology. In 3 cases with the solid pattern, the ultrasound appearance suggested ovarian malignancy. When the clinical setting and the age of the patient are suggestive of endometriosis, the sonographer should consider this possibility in his differential diagnosis of pelvic masses, regardless of the consistency of the lesion.

Interesting, unusual, and confusing renal cysts from a group of 200 cysts punctured percutaneously during the past decade are presented. Some cases illustrate pressure phenomena in cysts adjacent to each other or causing calyceal obstruction. Also reported are cyst wall findings, unusual cyst configurations, infection in pre-existing cysts, examples of cysts simulating renal cell carcinoma, and renal cell carcinoma presenting as cysts. In unusual cases, percutaneous needle puncture remains the procedure of choice for establishing the diagnosis of benign simple cyst versus malignancy or infection, or for determining the relationship of a cyst with the collecting system or with other cysts. Cyst puncture may also result in iatrogenic changes.

It has been claimed that the distinction between a simple cyst and a simple noncomplicated hydatid cyst cannot be made by ultrasound examination. It is very important to make this distinction before attempting a diagnostic or therapeutic puncture of a cyst, at least in geographic areas where echinococcosis is endemic. The authors report an ultrasound sign that makes this differential diagnosis possible.

The ambient cistern and the adjoining CSF spaces are typical locations of epidermoid cysts, lipomas, and arachnoid cysts (2, 3, 4, 7, 8). Since 1975 at the neurosurgical departments of Munich (1975–1979) and Berlin-Charlottenburg (1980–1984), 17 patients with epidermoid cysts, arachnoid cysts, and lipomas of this region have been observed. Surgical treatment has been performed in 14 of them. This group contained 10 epidermoid cysts, two arachnoid cysts, one lipoma, and one so-called simple cyst (6). In the remaining three patients the lesion was found incidentally and did not produce signs and symptoms. The probable diagnoses in these cases are: lipoma (two patients) and arachnoid cyst (one patient). The mean age of the operative group was 34.2 years, the youngest being three years old (arachnoid cyst), the oldest 49 (epidermoid). Both sexes were affected equally.

Basic technique of evaluating renal mass lesions is presented. The analytic criteria of separating cystic from solid lesions are reviewed along with the differential points of the intermediate mass lesion that does not meet the classical hallmark of a simple cyst. Experience has shown that sonography could be the first evaluation step in a renal mass since it is not invasive, does not employ ionizing radiation, and is cost effective.

We report a case of a simple cyst in the upper pole and connected to the mediastinum testis at the rete testis. The cyst appeared to arise from a dilated rete duct, and it was spherical, smoothwalled and filled with clear fluid. The epithelium was lined with a single layer of cuboidal or flattened cells, with no evidence of squamous differentiation.

Of 815 renal masses studied by computed tomography (CT), 60 did not fit the criteria for cyst or neoplasm and thus were called indeterminate. When artifacts were present, the likely diagnosis was a simple cyst; when no artifacts were present to explain atypical features in cyst-like masses, further investigation was necessary. Angiography was useful in only 16%, while ultrasound combined with cyst aspiration was diagnostic in 84%. All solid lesions required surgical investigation. Ultrasound with or without aspiration is recommended for all cyst-like renal masses thought to be indeterminate on CT.

Percutaneous renal cyst puncture under fluoroscopic control has gradually become accepted as the definitive step in the diagnosis of uncomplicated simple cyst of the kidney (Sherwood and Stevenson, 1971; Lalli, 1972; Thornbury, 1972) and may succeed as a therapeutic manoeuvre (De Weerd, 1962) although few cysts actually require treatment. This paper describes the extension of this procedure to the diagnosis and treatment of infection of a simple renal cyst. A 55-year-old woman was admitted to hospital in diabetic precoma. Previously, her diabetes had been well controlled by oral Diabenese. After her resuscitation with intravenous fluids and insulin, she was found to have a pyrexia of 38°C, a leucocytosis of 15,000 per mm3, and slight tenderness in the right flank. Klebsiella aerogenes was cultured from the urine.

As mentioned in the introduction there are now sufficient sophisticated techniques available to allow a systematic approach to the investigation of renal masses in the shortest possible time and with minimal unpleasantness and hazard to the patient. Table 4.1 illustrates the investigative sequence that is widely followed when a mass is found on intravenous urography.

A series of 636 consecutive knee arthrotomies was subjected to a prospective study, including the incidence, clinical presentation, and operative findings of meniscal cysts and associated pathological conditions. The clinical differential diagnosis was studied in detail, and from this, the importance of a specific clinical sign indicating a torn lateral meniscus was realized. This sign was termed a "pseudocyst". It was concluded that meniscectomy was the operation of choice and not simple cyst removal, and that the high incidence of associated meniscal tears and other less frequent joint pathological conditions justified a standardized approach designed to assess the meniscus and other intraarticular structures, rather than a simple incision over the joint-line swelling.

Six patients with cystic liver tumours are presented. The definitive diagnosis of such cystic lesions may be difficult and needle aspiration or biopsy or even operation may be necessary. Clinical and biochemical features may be helpful and in five of the six patients presented, the liver function tests were abnormal. In two patients, diagnostic imaging could not distinguish the tumour from a benign cyst. The differential diagnosis of such cystic liver tumours includes simple cyst, polycystic liver disease, hydatid, liver abscess, haematoma and biloma.

Ultrasound examination of nine patients revealed that the appearance of their hemorrhagic pancreatic fluid collections varied depending on the age of the hemorrhage. Acute hemorrhage was visualized as a well-defined homogeneous mass, while subacute hemorrhage (studied about a week after the bleeding episode) appeared as a mass that contained cystic and solid elements or was septated. Remote hemorrhage, studied several weeks after the acute event, was visualized as a simple cyst. Findings of CT, which were available for correlation in eight patients, revealed that acute hemorrhagic collections had CT numbers between 45 and 65 HU: older collections had CT numbers between 14 and 25 HU. The ultrasonographic evolution of hemorrhagic pancreatic fluid collections followed a pattern similar to that described by in vitro studies, which determined that hemorrhage and clotted blood may appear either echogenic or sonolucent, depending on the age of the hemorrhage and the transducer used. Factors that affect the echogenicity of hemorrhagic collections and the difficulties encountered in recognizing them by ultrasound are discussed.

The differential diagnosis and investigation of simple cysts has been described in the previous chapter. Three other cystic lesions of the kidney will be considered in this chapter.

The simple cyst in the adult seems to be mainly an acquired disorder. Microdissection of the nephron in the adult kidney points to the presence of diverticula on the distal tubule as the starting point of the affection. A degree of obstruction in the urinary tract together with normal involutional phenomena of the basal membrane, both typical of the aging process, are believed to be precipitating factors.

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A case of a calcified, simple cyst of the kidney with an unusual lining epithelium is presented. A possible etiologic basis is suggested.

While fluid collections within the scrotum are not uncommon, an uncomplicated cyst attached to or within the various components of the scrotum is unusual. We report a case of a rare simple cyst of the testicle, which was diagnosed accurately by preoperative ultrasound examination.

症例. 64才,女性.心窩部痛のため来院.アミラーゼ, CEA, CA19-9の高値を認めたため精査入院. ERCPにて総胆管下部内腔に突出する隆起性病変を認めた.さらに精査したが悪性病変も否定できないため膵頭十二指腸切除術を施行.手術の結果,病変は膵内胆管壁内に存在するのう胞性の粘膜下腫瘍であった.胆道系の良性腫瘍はまれで,その中でも総胆管壁内の単のう胞は極めてまれな疾患である.

A 17-year-old girl was hospitalized for evaluation of gradually decreasing function of a kidney transplanted 8 years earlier. A plain film of the abdomen showed a possible renal calculus. Excretory urography proved that this calcification was slightly anterior to the kidney but in the upper pole a well rounded mass was discovered. An echogram confirmed the diagnosis of benign renal cyst.Malignant cystic lesions obviously must be differentiated from those that are benign. Patients on immunosuppressive therapy are known to have a higher incidence of malignancy than the general population. A malignant tumor may require withdrawal of immunosuppressive therapy and removal of the transplanted organ, whereas a benign cyst would require no therapy unless it becomes infected or produces obstruction.

Ultrasound (US), because of its ability to distinguish cystic from solid tissue, is an ideal tool for diagnosing masses in the popliteal fossa. Five cases are presented. Two cases show the typical ultrasound images in the most common popliteal mass, a cyst. A third case significantly points out the necessity of further investigations if the US findings are atypical of a simple cyst and the patient is symptomatic. A fourth case demonstrates that the US image can distinguish an aneurysm of the popliteal artery from a cyst. A fifth case demonstrates that a solid tumor in the popliteal fossa, in contrast to that of a cyst, has a characteristic US image. Ultrasound is a simple, quick, noninvasive outpatient procedure available to almost every physician. In most instances, US appears to be the diagnostic procedure of choice following conventional radiography in the evaluation of swelling in the popliteal fossa.

In the 40 cases of cystic adventitial disease of the popliteal artery reported in the world literature, 20 patients have been treated by graft replacement with two of four synthetic graft failures and two of 14 vein-graft failures. Simple cyst evacuation has succeeded in all but two of 19 cases and reevaluation of cyst has succeeded in both of the evacuation failures. The condition causes severe calf claudication in young men, but does not progress to severe ischemia nor need for amputation, even with failure of arterial reconstruction. Etiology of the condition is obscure but may be related to cellular incorporation of mucin-secreting cells within the arterial adventitia.

• It is necessary to classify cystic disorders of the kidney with care because the prognoses of the various entities are quite different, depending on the type of the cysts, whether single or multiple, unilateral or bilateral, simple or complicated, painful or asymptomatic. The nature of the liquid found in the cyst helps to decide whether the lesion is to be considered malignant. Gross specimens, schematic diagrams, and pyelograms are shown to illustrate simple cyst, unilateral cyst with papillary carcinoma visible on part of the wall, cyst secondary to tuberculous pyelonephritis, bilateral familial diffuse cystic disease with preservation of the reniform organ contours and of functioning nephrons, unilateral cystic disease with destruction of both form and function, and other types of cysts that surround all or part of the kidney. The experiences of the authors lead to the conviction that the standard treatment of bilateral familial polycystic disease of the kidneys remains medical except when specific complications exist.

Many papers have been written concerning heredity as a factor in the development of tumors in the human body. Blank, 1 in 1941, reviewed the role of genetics in cancer research. Recently, we had occasion to treat the fourth member of a family to have a tumor of the brain. The occurrence of tumor of the brain in 4 members of one family strongly suggests a familial tendency in certain types of cerebral neoplasms. The predominating type of tumor identified in our cases was hemangioblastoma of the cerebellum. Cushing and Bailey, 2 in 1928, described at length many cases of this tumor. These growths were classified as simple cyst or gliomatous cyst until portions were removed for microscopic examination and a diagnosis of hemangioblastoma was made. The neoplasm occurs almost exclusively in the cerebellum, is usually cystic and has a familial tendency (Sargent and Greenfield 3 ). Characteristically, but not always