Extratesticular neoplasms are rare but clinically significant lesions that affect patients of all ages. These neoplasms are generally asymptomatic but may have potentially life-threatening sequelae. Lipoma is the most common primary benign paratesticular neoplasm and the most common tumor of the spermatic cord. Adenomatoid tumor is the most common tumor of the epididymis, followed by leiomyoma. In adult patients, it is imperative to consider sarcomas in the differential diagnosis of all solid tumors of the scrotum. The most common sarcomatous tumors in pediatric patients are embryonal sarcoma and rhabdomyosarcoma. Metastases, particularly from testicular, prostatic, renal, and gastrointestinal primary malignancies, can also occur. Mimics of paratesticular neoplasms including polyorchidism and splenogonadal fusion are rare but must also be considered for optimal management. Ultrasonography (US) is currently the imaging modality of choice. However, US findings are often variable and nonspecific and do not usually allow definitive characterization. Specific computed tomographic and magnetic resonance imaging findings with respect to tumor location, morphologic features, and tissue characteristics can aid in the evaluation of paratesticular neoplasms and help narrow the differential diagnosis.

To develop consistency in terminology and pathologic criteria, the authors reviewed the literature and 213 cases of neuroblastic tumors (NT) registered with Pediatric Oncology Group (POG) protocols 8104 and 8441. The patients were given standardized therapy stratified according to POG stage and patient age, and four or more histologic sections of primary tumor resected before therapy were available in each of these 213 cases. All stages were represented. The recommended nomenclature combines conventional terms and criteria with those used by Bove and McAdams and Shimada et al. The main features of the recommended nomenclature are as follows: (1) the terms neuroblastoma (NB) and ganglioneuroblastoma (GNB) are retained instead of stroma‐poor NB and stroma‐rich NB, recommended by Shimada et al.; (2) undifferentiated NB is considered a subtype separate from poorly differentiated NB; and (3) the term GNB is used only when there is a predominant ganglioneuromatous component admixed with the minor neuroblastomatous component. With the use of these criteria and terms, the Shimada classification was determined in the 213 cases. The results showed that, even after stratification for age, POG stage, and primary site, there is a statistically significant difference in survival rate between favorable histologic and unfavorable histologic prognostic subgroups. The authors recommend that definitive prognostic categorization of an NT according to Shimada classification should be done only when adequate histologic material is available from a primary tumor resected before any other therapy. Categorization done on histologic material from small biopsy specimens, previously treated primary tumors, or meta‐static sites should be considered tentative.

Most studies that have examined minimally invasive, encapsulated, follicular carcinoma (FC) or Hurthle cell carcinomas (HCs) have contained only a few metastatic neoplasms. We studied 34 patients with a single, minimally invasive, metastatic FC or HC and compared them with 38 patients with similar, nonmetastatic FCs or HCs. The numbers of incomplete capsular penetration (neoplasm into but not through the capsule), complete capsular penetration (neoplasm through the capsule), and vascular invasion foci were quantified. The median number (three), range, and distribution of complete capsular penetration and vascular invasion foci were similar in the nonmetastatic and metastatic carcinomas. All of the metastatic FCs and HCs had at least one vascular invasion or complete capsular penetration focus. Sixty-two percent of the metastatic carcinomas had two to four complete capsular penetration foci, and 60% had two to four vascular invasion foci. Two metastatic neoplasms had incomplete capsular penetration but had one and two vascular invasion foci, respectively. One tumor had no vascular invasion but had four complete capsular penetration foci. No metastatic neoplasms had incomplete capsular penetration only. There were no differences in the number of vascular invasion or complete capsular penetration foci between metastatic and nonmetastatic FCs and HCs and between metastatic FCs and HCs. Most metastatic neoplasms had vascular space invasion and complete capsular penetration. The number of complete capsular penetration or vascular invasion foci was not associated with the initial site of metastasis or the interval between the surgery and the metastasis.

Histologic sections (minimum of four sections per patient) from 211 patients with neuroblastoma were reviewed. The tumors were resected before therapy, which was standardized according to age and stage. Low mitotic rate (MR) (≤ ten per ten high‐power fields) and calcification emerged as the most significant prognostic features after statistical analysis by stepwise log‐rank tests (P < 0. 0001 and P = 0. 0065, respectively). Histologic Grades 1, 2, and 3 were defined on the basis of the presence of both, any one, or none of these two prognostic features, respectively (Grade 3 had absence of low MR, i.e., these tumors had high MR [> ten per ten high‐power fields]). Statistically significant differences in survival were observed in the grades after adjusting for age and stage (P < 0. 001). The degree of differentiation, although significant by itself, was no longer significant after adjusting for the grades, Age groups (≤ 1 versus > 1 year of age), which also emerged as an independent prognostic feature (P < 0. 001), were linked with the grades to define two risk groups as follows: (1) a low‐risk (LR) group consisting of patients in both age groups with Grade 1 tumors and patients 1 year of age or younger with Grade 2 tumors and (2) a high‐risk (HR) group consisting of patients older than 1 year of age with Grade 2 tumors and patients in both age groups with Grade 3 tumors. The difference in survival between LR (160 cases) and HR groups (51 cases) was statistically significant (P < 0. 001). Concordance between these LR and HR groups and the Shimada classification was observed in 84% of cases. The new histologic grading system has the following advantages: (1) use of familiar terminology and histologic features in the grading system and (2) relative ease of assessment because the degree of differentiation does not need to be determined. The grading system should be tested on a new data set with an appropriate histologic sample of similar size to confirm these results.

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