Histological features and prognostic significance of treatment effect in lymph node metastasis in head and neck squamous cell carcinoma.

AIMS AND OBJECTIVES: Cervical lymph node metastasis in head and neck squamous cell carcinoma (HNSCC) is common. Pre-operative chemoradiotherapy (preCRT) and postoperative chemoradiotherapy (postCRT) is frequently employed in such patients. The prognostic value of viable SCC, treatment effect or no SCC in resected lymph nodes in patients who received or did not receive preCRT and postCRT was investigated. METHODS AND RESULTS: Resected cervical lymph nodes from 146 patients with HNSCC were evaluated for viable SCC, treatment effect or no SCC. Immunostains for Ki67, cyclin D1, caspase 3 and H2AFX were performed on viable SCC or nucleate keratin debris. Clinical and histological data were correlated with tumour recurrence or persistence. Patients with nucleate keratin debris in lymph nodes had outcomes similar to those with diffuse treatment effect and no SCC. Viable tumour in lymph nodes was associated with worse prognosis in patients who received preCRT (P = 0.01). This relative worsening of prognosis was not observed in patients with oropharyngeal SCC or recurrent disease. Lower proliferation index in lymph node SCC was associated with preCRT and with worse outcomes (P = 0.0002). Overall, patients who received preCRT or postCRT had outcomes not significantly different from those who did not. CONCLUSION: The presence of viable SCC in cervical lymph nodes has prognostic import when taken in context with the patient's history. Viable SCC in lymph nodes was significantly associated with worse outcome among patients with non-oropharyngeal SCC who received preCRT. Nucleate keratin debris should not be considered viable SCC in lymph nodes.

Natural History and Malignant Transformation in Recurrent Respiratory Papillomatosis: Human Papillomavirus (HPV), Dysplasia and an Autopsy Review.

INTRODUCTION: Recurrent respiratory papillomatosis (RRP) is a human papillomavirus (HPV) related disease in both children and adults, characterized by recurrent benign squamous papillomas of the respiratory mucosa. Malignant transformation is rare. The present report concerns the natural history of RRP in two children. MATERIALS AND METHODS: Clinical records, autopsy material and tissue from previous surgical excisions were reviewed in both cases. Select surgical and autopsy specimens were examined using p16 immunohistochemistry and in-situ hybridization for low and high risk HPV. RESULTS: Both children had pulmonary involvement with incidental invasive keratinizing squamous carcinoma of the lung at autopsy. Low-risk HPV was present in the papillomas and carcinoma at autopsy in both cases. CONCLUSIONS: The autopsy examinations in these two cases emphasize the serious, if uncommon, pulmonary complications of this disease. In conjunction with previously reported autopsies, destructive lung disease may be as frequent a cause of death as disseminated malignancy.

Low-grade prostate cancer diverges early from high grade and metastatic disease.

Understanding the developmental relationship between indolent and aggressive tumors is central to understanding disease progression and making treatment decisions. For example, most men diagnosed with prostate cancer have clinically indolent disease and die from other causes. Overtreatment of prostate cancer remains a concern. Here we use laser microdissection followed by exome sequencing of low- and high-grade prostate cancer foci from four subjects, and metastatic disease from two of those subjects, to evaluate the molecular relationship of coincident cancer foci. Seventy of 79 (87%) high-confidence somatic mutations in low-grade disease were private to low-grade foci. In contrast, high-grade foci and metastases harbored many of the same mutations. In cases in which there was a metastatic focus, 15 of 80 (19%) high-confidence somatic mutations in high-grade foci were private. Seven of the 80 (9%) were shared with low-grade foci and 65 (82%) were shared with metastatic foci. Notably, mutations in cancer-associated genes and the p53 signaling pathway were found exclusively in high-grade foci and metastases. The pattern of mutations is consistent with early divergence between low- and high-grade foci and late divergence between high-grade foci and metastases. These data provide insights into the development of high-grade and metastatic prostate cancer.

The Stapes in Otosclerosis: Osteoarthritis of an Ear Ossicle.

Otosclerosis is a pagetoid proliferation of bone remodeling, vascular proliferation, bone resorption and new bone formation in the tympanic region of the temporal bone. The resulting anklyosis of the stapes footplate as it articulates with the oval window is the most common cause of conductive hearing loss in young to middle aged, predominantly Caucasian individuals. The characteristic histologic features have been well documented by autopsy studies of the temporal bone. Although stapedectomy is the surgical treatment for otosclerosis, the stapes specimen may be submitted for gross examination only or not examined at all. A retrospective study of 73 stapedectomy specimens (2008-2019) not including the stapes footplate. Clinical features from the electronic medical record as well as standard histologic sections from surgical specimens were reviewed. Neither the stapedal head nor crura showed histologic features of otosclerosis. There was mild osteoarthritis affecting the head, possibly as a consequence of persistent ossicular vibration superimposed on the ankylosed rigidity. The most common changes were surface fissuring (65%), cartilaginous erosion (49%) and irregularity of the osteochondral interface (51%). An occasional osteophyte (8%) was observed. The ear ossicles, embryologically analogous to long bones of the extremities, develop via endochondral ossification and exhibit articular surfaces of hyaline cartilage. The present observations suggest that a consequence of otosclerotic ankylosis is osteoarthritis of the stapedal head. In this study, the histological features could not be correlated with the severity of hearing loss or duration of clinical disease.

Distinguishing Parathyromatosis, Atypical Parathyroid Adenomas, and Parathyroid Carcinomas Utilizing Histologic and Clinical Features.

Parathyromatosis is displaced parathyroid tissue in the neck and mediastinum related to prior surgery. Parathyromatosis can be difficult to distinguish from atypical adenoma and parathyroid carcinoma. The aim of this study is to evaluate clinical and morphologic features that may differentiate parathyromatosis, atypical adenoma, and parathyroid carcinoma. Cases of parathyromatosis, atypical adenoma, and parathyroid carcinoma were identified. Index cases were reviewed by consensus for histologic features, including stromal, cytologic/architectural, and invasive features. Ki67 was performed on index cases and scored using the Adsay method. Clinical information was gathered from the electronic medical record. 4 parathyromatosis, 17 atypical adenoma, and 6 parathyroid carcinoma were included. Parathyroid carcinomas were more likely to display coarse chromatin with nucleoli (P = 0.04), infiltrative invasion (P < 0.01), and metastasis (P < 0.01). Only parathyromatosis showed circumscribed invasion. Infiltrative invasion was more common in cases with progression (P = 0.046) and metastasis (P < 0.001). Necrosis and perineural invasion were only present in cases with progression and were more frequent in cases with metastasis (P = 0.079 and P = 0.19, respectively). There were no differences in presence of a fibrous capsule, capsular invasion, intralesional fibrous bands, random endocrine atypia, solid growth, Ki67 index, gland size/weight, serum PTH/calcium levels, and locoregional recurrence rates. There is overlap in the histologic features in parathyromatosis, atypical adenoma, and parathyroid carcinoma. While perineural, vascular, and infiltrative soft tissue invasion should remain diagnostic of malignancy, other atypical features such as solid growth, coarse chromatin with nucleoli, and necrosis should raise concern for recurrence and/or metastasis, and can be present in parathyroid lesions with and without recurrence.

Intraoperative frozen section assessment of pelvic lymph nodes during radical prostatectomy is of limited value.

OBJECTIVE: To evaluate the accuracy of frozen section (FS) assessment of pelvic lymph nodes (PLNs) during radical prostatectomy (RP) in a large contemporary cohort; and to analyse the contribution of FS to surgical decision making in this setting. PATIENTS AND METHODS: During a 4-year period at a single institution, RPs with PLN dissection (PLND) were reviewed. The number and size of the PLNs, and the size of metastases were measured. RESULTS: FS was performed on 349 bilateral PLNDs. Overall, 28 (8%) cases were positive for metastasis, 11 of which were detected by FS (39%). The 17 false negatives, all of which contained metastases smaller than 5 mm, were due to failure to identify and freeze the positive PLNs (11), failure to section at the level of the metastatic tumour (four), or interpretative error (two). The sensitivity was not affected by the number of sampled nodes. The size of metastasis was the determining factor for the accuracy of FS, with metastases of ≥ 5 mm having a sensitivity of 100%, and metastases of < 5 mm having a sensitivity of 10%. Among the 11 true positives, RP was aborted in eight cases and continued in three. During the same period, 261 PLNDs were performed without FS, and 18 (6.9%) had metastases. CONCLUSIONS: FS is highly accurate in detecting large, grossly evident metastases, but performs poorly on micrometastases. It is recommended that a two-step approach applied to routine FS starting with a careful gross examination followed by FS for only grossly suspicious PLNs.

Educational Case: Yolk Sac (Endodermal Sinus) Tumor of the Ovary.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

Syphilis: A Contemporary Clinicopathologic Assessment.

Syphilis is a sexually transmitted disease caused by the spirochetal bacterium Treponema pallidum that has been of public health concern for centuries. In the United States, it is currently a reportable disease and one which is recently generating increasing case numbers especially in at risk populations of immune deficiency and men who have sex with men. The present series examines biopsies from 13 patients collected over a 12-year period from a general hospital network in north suburban Cook County, Illinois. There were 13 patients (11 male: 2 female) with varied presentations, including primary ulcerated anogenital chancres, mucosal lesions, peculiar rashes, and alopecia. The reason(s) for biopsy were not clear from the clinical record, as a clinical consideration of syphilis was recorded in only 3 cases. Histologic examination of the mucocutaneous lesions encompassed a spectrum of findings including ulceration, psoriasiform hyperplasia, intense mixed band-like inflammation at the dermal-epidermal junction with a prominent plasma cell component. The contemporary availability of an effective immunostain is a valuable diagnostic adjunct. The organisms generally parallel the intensity of the inflammatory infiltrate but the distribution may vary and rarely, organisms may be absent despite serologic confirmation. Previous corkscrew morphology of the organism described ultrastructurally is reflected in the immunostained representation. Although the diagnosis of syphilis remains a clinical one in most cases, some patients will have unusual presentations and biopsies will be done. The awareness of the pathologist will facilitate prompt and effective treatment.

Atypical Laryngeal Infections: Localized Lesions from Unusual Organisms May Simulate Malignancy.

OBJECTIVE: The identification of rare sources of laryngeal infection in immunocompetent patients. Recovered organisms were Mycobacterium tuberculosis (laryngeal tuberculosis [LTB]), Mycobacterium fortuitum (laryngeal Mycobacterium fortuitum [LMF]), and Blastomyces dermatiditis (laryngeal blastomycosis [LB]). METHOD: Single institution retrospective case series of three patients over a 2.5-year period and review of the literature on laryngeal infections by three atypical organisms. RESULTS: Three patients presented with hoarseness and cough; one additionally had throat pain (LTB). Indirect laryngoscopy demonstrated diffuse laryngeal ulceration (LTB, LMF) and an exophytic, contiguous glottic mass (LB). Direct microlaryngoscopic biopsies and cultures established the diagnoses, including a frozen section in one case (LB), which prevented a simultaneously planned surgical resection. Appropriate antimicrobial therapy yielded dramatic laryngeal and corresponding vocal improvement, for which we provide unique photo and audio documentation. In the last 10 years, fewer than 500 cases of LTB have been reported in the English language medical literature, principally outside the United States. To date, there have been reports of only 34 LB and no cases of LMF. CONCLUSION: Atypical infections of the larynx may be localized and mimic laryngeal cancer on endoscopy. Tissue examination as well as microbiologic samples are diagnostic and complementary.

Recutting prostate needle core biopsies with high grade prostatic intraepithelial neoplasia increases detection of adenocarcinoma.

OBJECTIVES: We sought to evaluate the ability of biopsy core recutting to increase cancer detection in patients with high grade prostatic intraepithelial neoplasia (HGPIN). METHODS: This prospective study encompasses all patients undergoing 12 core TRUS guided prostate biopsy between February 2004 and January 2007. In patients with HGPIN on initial biopsy, the paraffin blocks were resampled for cancer by additional deeper levels per core. Additional analysis was performed in the patients with HGPIN in order to detect whether significant differences in prebiopsy variables were associated with patients subsequently found to have benign versus carcinoma on recutting. Last, the costs associated with this procedure were studied. RESULTS: Forty of 584 (6.8%) patients undergoing prostate biopsy were found to have HGPIN in the absence of prostatic adenocarcinoma on initial histopathology. Following recutting, 12.5% (5/40) of these patients were found to have prostatic adenocarcinoma not previously detected. Of the remaining 35 patients, 18 underwent repeat biopsy. Of these, five patients were found to have adenocarcinoma and three were found to have persistent HGPIN. The PSA, PSA density (PSAD), and PSA velocity (PSAV) prior to initial biopsy were not statistically different when comparing patients found to have benign tissue versus carcinoma on recutting. In patients with HGPIN, at our institution, recutting the biopsy would yield a cost savings of $436/patient as opposed to universal rebiopsy. CONCLUSIONS: Our data suggest that prostate biopsy recutting may increase cancer detection in patients initially found to have HGPIN. Additionally, a significant cost savings is associated with the recutting protocol.

Cutaneous Leishmaniasis: Contribution of Routine Histopathology in Unexpected Encounters.

The ulcerated papules of cutaneous leishmaniasis represent an unusual form of granulomatous dermatitis caused by Leishmania species, a protozoan transmitted by sandfly bites. As the disease is not native to North America, clinical suspicion is partially based on a compatible travel history and may result in a biopsy. The key role of standard morphology is the identification of Leishmania organisms, supplemented by Giemsa and/or CD1a immunostaining. Histologically, the organism may be confused with Histoplasma species, which is resolved by staining with methenamine silver or PAS. Four cases of cutaneous leishmaniasis are presented for which organisms were present in 3; polymerase chain reaction and DNA sequencing for speciation done by the Center for Disease Control and Prevention (CDC) was confirmatory in 3 cases, including the one case without histologically identifiable organisms. Rare unexplained cases of cutaneous leishmaniasis without a travel history have been reported outside endemic areas. The present cases emphasize the importance of diagnostic awareness of unusual infections such as this in the context of political unrest, ease of international travel, climate change and the possible expansion of geographic vector distribution. In the morphologic absence of organisms, the diagnosis may require molecular techniques, currently available on a referral basis to pathologists without charge from CDC.

Blastomycosis: contributions of morphology to diagnosis: a surgical pathology, cytopathology, and autopsy pathology study.

Blastomycosis is caused by the inhalation of spores of the dimorphic fungus, Blastomyces dermatitidis. The reporting of this disease is not required by all states. The diagnosis is established by culture or by identification of broad budding yeast forms in tissue or cytology samples. A retrospective review of blastomycosis was conducted using surgical pathology and cytopathology records of a large community based general hospital, for the years 1982 to 2002; the autopsy records of a university referral center were searched for the years 1992 to 2004. Thirteen surgical/cytology cases were retrieved: 8 localized to the lung (group 1) and 5 with extrapulmonary presentation (group 2). Three of the former were clinically thought to be tumors. Broad-based budding yeast forms with thick cell walls were seen in all but 1 case and identified on conventional routinely stained preparations. Microbiologic culture was positive in 2 lung cases only, in 1 of which it was the sole means of diagnosis. Culture was negative for Blastomyces in the only extrapulmonary case for which a specimen was submitted. One patient in group 2 died, but had a coexistent disseminated gastric adenocarcinoma. No autopsy was performed. Three autopsies of blastomycosis were recovered (group 3). Two patients were on corticosteroids and 1 was diabetic. Premortem diagnoses were established only within a few days of death in 2 patients. Blastomycosis is seldom a fatal disease. Most patients are immune competent; immune compromise favors an aggressive course. Microbiologic culture and conventional morphologic assessment of routine samples have redundant utility in diagnosis.

Pneumocytic adenomyoepithelioma: a distinctive lung tumor with epithelial, myoepithelial, and pneumocytic differentiation.

Pulmonary tumors with epithelial and myoepithelial differentiation are rare, thought to be of bronchial minor salivary gland origin and classified similarly to salivary gland neoplasms. We report a series of a distinctive subtype of pulmonary glandular tumors showing epithelial and myoepithelial differentiation with further pneumocytic specialization. All patients were women, aged 52 to 63 years and presented with single or multiple pulmonary nodules. The tumors were grossly circumscribed, 0.8 to 2.6 cm in greatest dimension, and histologically showed glandular and spindle cell differentiation. Some glands were filled with colloidlike secretion and had an inner, cuboidal epithelial cell layer (pankeratin, epithelial membrane antigen, and thyroid transcription factor-1 positive), surrounded by an outer layer of myoepithelial cells merging with foci of spindled myoepithelial cells (high molecular weight keratin, S100, smooth muscle actin, calponin, caldesmon, and p63 positive). There were also some glands lined by a single layer of plump cells that were positive for surfactant protein-A in addition to the other epithelial cell markers. Electron microscopy confirmed pneumocytic features in these cells and the myoepithelial nature of the spindled cells. The surgery in all cases was wedge resection of the masses. The biologic behavior to date has been benign. This is the first reported series of a distinctive lung tumor with epithelial, myoepithelial, and pneumocytic differentiation that differs histologically from all previously recognized pulmonary salivary gland-type and pneumocytic tumors. It is a unique benign appearing neoplasm for which the designation pneumocytic adenomyoepithelioma is suggested.

Utility of lip biopsy in the diagnosis and treatment of Sjogren's syndrome.

OBJECTIVE: Sjogren's syndrome (SS) is an autoimmune disease involving primarily the salivary and lacrimal glands ("sicca" symptoms) with extraglandular features including joint and nervous system involvement. In patients with a questionable diagnosis of SS but severe extraglandular symptoms, a lip biopsy is often performed to firmly establish the diagnosis of SS. This study was undertaken to identify areas of uncertainty regarding the accuracy of biopsy interpretation and the diagnostic benefits of the procedure. STUDY DESIGN: : Retrospective review of clinical and pathologic data. METHODS: Clinical data from 47 patients referred to the otolaryngology-head and neck surgery service for lip biopsy were reviewed. Archival pathologic specimens were scored using the currently accepted grading system. RESULTS: The grading system was incorrectly applied during initial interpretation of 45% (n = 21) of specimens. This resulted in five (10%) pathologic misdiagnoses and 16 (34%) nondiagnoses. On re-interpreting the specimens with consistent application of the grading system, 62% (n = 29) of the biopsies were definitely positive, and 36% (n = 17) were negative. Neither positive serology nor the presence of sicca symptoms predicted a positive biopsy (likelihood ratio = 0.95 and 0.96, respectively). Lip biopsy guided treatment in at least 65% (n = 31) of patients but was ignored in the presence of other clinical findings in 17% (n = 8) of patients. CONCLUSIONS: Consistent application of the grading system is essential in avoiding incorrect diagnosis and aiding clinical decisions. However, not all patients undergoing lip biopsy will derive diagnostic benefit from the procedure. In this series, clinical symptoms and serology did not predict positive lip biopsy.

Sural nerve grafting in robotic laparoscopic radical prostatectomy: interim report.

BACKGROUND AND PURPOSE: Sural nerve grafting for patients undergoing prostatectomy has been previously reported using open and minimally invasive methods. We report our experience with sural nerve grafting during robot-assisted laparoscopic radical prostatectomy (RLRP). MATERIALS AND METHODS: Patients with preoperative potency and a minimum of 6 months follow-up were included in this prospective review. A total of 333 patients were identified between February 2003 and January 2006 who met these criteria including 22 of the 25 patients who underwent sural nerve grafting. Patients were divided into 5 groups to compare unilateral and bilateral sural nerve cohorts with non-nerve-sparing and unilateral and bilateral nerve-sparing groups. Patients were followed prospectively using health-related quality-of-life questionnaires. RESULTS: Twenty-two patients underwent sural nerve grafting that included three bilateral grafts. Mean follow-up was 14 months. There was no statistical difference in patients' ages, body mass index, preoperative prostate-specific antigen level, blood loss, complications, and positive margin rate. Operative time was statistically longer for both sural graft cohorts when compared with unilateral (without graft) and bilateral nerve sparing cohorts. No significant differences in subjective or objective sexual function, sexual bother, or urinary function were seen with 6 and 12 months follow-up, possibly related to smaller sural cohorts. Graft-related complications include leg pain in one patient. CONCLUSION: Sural nerve grafting during RLRP is technically feasible and safe and offers improved dexterity and visualization deep within the pelvis. However, a larger randomized cohort of patients will be required to validate any improved benefits afforded by the robot system.

External validation of a nomogram for prediction of side-specific extracapsular extension at robotic radical prostatectomy.

BACKGROUND AND PURPOSE: Several staging tools have been developed for open radical prostatectomy (ORP) patients. However, the validity of these tools has never been formally tested in patients treated with robot-assisted laparoscopic radical prostatectomy (RALP). We tested the accuracy of an ORP-derived nomogram in predicting the rate of extracapsular extension (ECE) in a large RALP cohort. PATIENTS AND METHODS: Serum prostate specific antigen (PSA) and side-specific clinical stage and biopsy Gleason sum information were used in a previously validated nomogram predicting side-specific ECE. The nomogram-derived predictions were compared with the observed rate of ECE, and the accuracy of the predictions was quantified. Each prostate lobe was analyzed independently. As complete data were available for 576 patients, the analyses targeted 1152 prostate lobes. Median age and serum PSA concentration at radical prostatectomy were 60 years and 5.4 ng/mL, respectively. RESULTS: The majority of side-specific clinical stages were T(1c) (993; 86.2%). Most side-specific biopsy Gleason sums were 6 (572; 49.7%). The median side-specific percentages of positive cores and of cancer were, respectively, 20.0% and 5.0%. At final pathologic review, 107 patients (18.6%) had ECE, and side-specific ECE was present in 117 patients (20.3%). The nomogram was 89% accurate in the RALP cohort v 84% in the previously reported ORP validation. CONCLUSIONS: The ORP side-specific ECE nomogram is highly accurate in the RALP population, suggesting that predictive and possibly prognostic tools developed in ORP patients may be equally accurate in their RALP counterparts.

Melanotic Translocation Renal Cell Carcinoma With a Novel ARID1B-TFE3 Gene Fusion.

A 36-year-old male was found to have a 7.0 cm left upper pole renal mass on renal ultrasound. Following nephrectomy, the mass was grossly ill-demarcated, friable and red-brown, invading renal parenchyma, hilar fat and the renal vein. Microscopically, the tumor had a nested and papillary architecture. The cells demonstrated abundant clear and eosinophilic cytoplasm and focal intracytoplasmic melanin pigment. Nucleoli were prominent. By immunohistochemistry, the tumor was positive for TFE3; HMB-45 stained approximately 5% of tumor cells corresponding to the histologic melanin pigment, which was confirmed with Fontana-Masson stain with bleach. Immunostains for PAX8, CD10, MiTF, and CAIX were negative; keratins Cam 5.2 and AE1/AE3 were focally positive. Targeted next-generation sequencing revealed an ARID1B-TFE3 gene fusion. Melanotic Xp11 renal cell carcinoma is a rare, pigment containing translocation variant demonstrating overlapping features with melanoma and is usually associated with an SFPQ-TFE3 gene fusion. The patient is alive and without evidence of disease 7 years after his diagnosis. The combination of high grade histopathology, the presence of melanin, absent PAX8, keratin positivity, and relatively indolent clinical behavior with a unique translocation may warrant recognition as a distinct renal cell carcinoma translocation subtype.

Echinococcosis: Unexpected Occurrence and the Diagnostic Contribution of Routine Histopathology.

Echinococcus is the smallest of the major tapeworms. Humans are incidental hosts who become infected by exposure to soil contaminated with ova from the feces of the canine definitive hosts. The major species are E. granulosus (cystic echinococcosis) and E. multilocularis (alveolar or sylvatic echinococcosis), both common worldwide but unusual and not reportable in the United States. Human disease is characterized by slowly growing visceral cystic masses often containing daughter cysts and hydatid sand. In nonendemic areas, the clinical evaluation includes imaging, serology, and surgery; metastatic tumor is a major consideration. The diagnosis depends on the morphologic recognition of scolices and hooklets, albeit degenerated, within the cyst or attached to the cyst wall. Highly suggestive cyst wall features are an acellular hyaline lining surrounded by focally calcific fibrous tissue and chronic inflammation. We report 7 patients encountered in the Chicago area (5 E. granulosus, 2 E. multilocularis) who presented with cystic masses affecting the liver, lung, soft tissue, and spleen. The initial diagnosis was established or suggested by intraoperative evaluation of cyst fluid or cyst wall histopathology. Organism parts were found in 5 cases; 1 patient had a hyalinized cyst wall with a positive IgG (enzyme-linked immunosorbent assay), and 1 had a positive Western blot and a 30-year history of treatment. Treatment included cyst resection, hepatic lobectomy, intraoperative cyst injection, and benzimidazole therapy. There was 1 death. In a nonendemic area, the awareness of the pathologist to the possibility of this disease will exclude a neoplasm and facilitate prompt antihelminthic treatment.