Liesegang rings in a submental mass: fine-needle aspiration with histologic correlation

Liesegang rings are lamellated concretions commonly found in chronic cystic lesions that are inflamed, necrotic, fibrotic, or hemorrhagic. We report on an unusual case of a 14-yr-old girl with an acute, rapidly enlarging solid submental mass in which Liesegang rings were identified on aspirate smears.

The small blue cell dilemma associated with tamoxifen therapy

CONTEXT

Several endometrial diseases, such as endometrial hyperplasia, endometrial carcinoma, and endometrial polyps, have been reported to be associated with tamoxifen administration. We recently observed a high incidence of distinctive small blue cells in Papanicolaou tests of women who had received tamoxifen treatment for breast carcinoma.

OBJECTIVES

To define the characteristics of these small blue cells, to identify the patient population in which they are found, and to determine the clinical significance and possible etiology of these findings.

DESIGN

A total of 154 Papanicolaou tests from 60 patients with a clinical history of tamoxifen therapy were reviewed retrospectively.

RESULTS

Small blue cells were found in 40% of Papanicolaou tests from patients who received tamoxifen therapy. Patients with small blue cells in their Papanicolaou tests were an average of 9 years older at the time tamoxifen therapy was initiated than those without. Among the available follow-up surgical biopsies, no malignant diagnoses were made.

CONCLUSIONS

We conclude that these distinctive small blue cells are found more frequently in older patients and most probably represent proliferative reserve cells of cervical/vaginal epithelium resulting from the estrogenic agonist effect of tamoxifen. More importantly, they are nonneoplastic in nature.

Quantitation of lipid-laden macrophages in evaluation of lower airway cytology specimens from pediatric patients

Quantitation of lipid-laden macrophages has been used as a tool in the diagnosis of aspiration-related respiratory disorders. Fifty-six respiratory specimens from pediatric patients with lung diseases were retrospectively reviewed, and lipid-laden macrophage indices were evaluated according to modified published grading methods. The indices from patients at high risk for aspiration were significantly different from those at low risk. A simpler and more reproducible grading method was introduced. An important issue regarding sample adequacy was also addressed.

Accuracy, utility, and cost of frozen section margins in head and neck cancer surgery

OBJECTIVES

Intraoperative frozen section analysis of surgical margins is widely used in head and neck cancer surgery. This study evaluates frozen section accuracy relative to permanent controls and final margins from the entire specimen, the rate at which frozen sections impact intraoperative management, and the resultant cost.

STUDY DESIGN

Retrospective.

METHODS

From 1997 to 1999 the frozen section results, permanent controls, and final tumor margins from 80 consecutive patients undergoing 420 intraoperative frozen section margins for head and neck malignancy were reviewed.

RESULTS

A 98.3% accuracy rate (sensitivity, 88.8%; specificity, 98.9%) was found compared with permanent sections of the same tissue. However, 40% (8 of 20) of patients with positive final margins on the resection specimen, and 100% (15 of 15) with close (<5 mm) margins were not detected by frozen section analysis. The overall accuracy of frozen section in the evaluation of close or positive final margins was 71.3% (sensitivity, 34.3%; specificity, 100%). In addition, 5% (4 of 80) of patients potentially benefited from intraoperative frozen section by virtue of immediate margin revision. The estimated cost of intraoperative frozen section averaged as much as $3,123 per patient, with a cost-benefit ratio of 20:1.

CONCLUSIONS

Intraoperative frozen section margins are accurate, but they are costly and cannot reliably eradicate positive final margins. Patients with early-stage lesions and those undergoing re-resection for recurrence or salvage surgery after radiation failure derived the greatest potential benefit from frozen section margins.

Adult herpetic laryngitis with concurrent candidal infection: a case report and literature review

Rarely, adult herpetic laryngitis without involvement of the oropharynx has been reported. However, to our knowledge, laryngitis caused by herpes simplex virus with coexisting Candida albicans has not been reported. We report what we believe to be the first case of localized herpetic laryngitis superimposed by laryngeal Candida species infection in an immunosuppressed patient. This diagnosis was made on the basis of the findings of a laryngeal mucosal biopsy and ancillary testing using fungal stains and immunohistochemical stains for herpetic antigens. We also review the literature and discuss the clinical and diagnostic presentations, including potential pitfalls in the diagnosis.

The clinical application and cost analysis of fine-needle aspiration biopsy in the diagnosis of mass lesions in sarcoidosis

BACKGROUND

Sarcoidosis is a prevalent disease of unknown cause characterized by granulomatous inflammation that often creates deep and/or superficial mass lesions. Tissue samples are considered the "gold standard" in diagnosis; however, it is a medically treated disease. We analyzed the utility and relative cost-effectiveness of fine-needle aspiration biopsy (FNAB) in the clinical investigation of patients with both suspected and unsuspected sarcoidosis.

METHODS

All FNAB cases with sarcoidosis either as the cytologic diagnosis or mentioned as part of the differential diagnosis were retrospectively reviewed for clinical history, follow-up, cytologic features, and surgical pathology findings. Comparative analysis of cost of FNAB and excisional biopsy were also made.

RESULTS

Thirty-two FNABs in 28 patients included 17 women and 11 men. Anatomic sites included lymph node (n = 17), lung (n = 5), salivary gland (n = 8), and liver (n = 2). Sarcoidosis had already been diagnosed or was a clinical consideration prior to FNAB in 14 cases. Chest radiograph showed abnormal findings in 19 cases. Angiotensin-converting enzyme (ACE) was measured in seven patients and was elevated in four. All aspirates showed granulomatous inflammation; in 22 patients, special stains or cultures for microorganisms were negative. Simultaneous or subsequent excisional biopsies confirmed the FNAB findings in 17 patients. Institutional ratios of excisional biopsy to FNAB in the diagnosis of sarcoidosis ranged from 4 to 19:1. The cost of FNAB was only 12.5 to 50% that of tissue biopsy.

CONCLUSIONS

FNAB appears to be underutilized in the diagnosis of sarcoidosis. When used in conjunction with radiologic and laboratory data, FNAB may be a reliable and cost-effective method of diagnosis, especially in patients with an established diagnosis of sarcoidosis.

Diagnosis of papillary carcinoma in a thyroglossal duct cyst by fine-needle aspiration biopsy

The incidence of papillary thyroid carcinoma arising in a thyroglossal duct cyst is rare and occurs in about 1 % of thyroglossal duct cysts. Only 17 such cases diagnosed with fine-needle aspiration biopsy have been previously reported in the English-language literature, with a diagnostic rate of 53%. In this article, the cytologic features of the current case are emphasized and those of the previous reported cases are briefly reviewed. Diagnostic pitfalls of papillary carcinoma arising in thyroglossal duct cysts diagnosed by fine-needle aspiration biopsy are also discussed.

Pleural fluid cytology of Hodgkin's disease: cytomorphologic features and the value of immunohistochemical studies

Two cases in which Hodgkin's disease (HD) was cytologically diagnosed in pleural effusions are presented. The presence of Reed-Sternberg (R-S) cells was confirmed by positive staining for both CD15 and CD30, and negative staining for leukocyte common antigen. In addition, the differential diagnosis of HD in effusion cytology is presented, including look-alikes of R-S cells that can potentially lead to an incorrect diagnosis. To the best of our knowledge, we believe this is only the second cytologic report of HD diagnosed in a pleural effusion using immunohistochemistry to confirm the diagnosis.

Anti-alpha-inhibin: marker of choice for the consistent distinction between adrenocortical carcinoma and renal cell carcinoma in fine-needle aspiration

BACKGROUND

Anti-alpha-inhibin, an antibody directed against a peptide hormone, has been shown to be a useful diagnostic aid in surgical pathology material for the identification of sex cord-stromal neoplasms and recently has been described in adrenocortical carcinoma (ACC). The diagnosis of ACC versus renal cell carcinoma (RCC) may be difficult morphologically, particularly in fine-needle aspiration (FNA) material. To date, the immunohistochemical distinction of ACC from RCC is based on a panel of antibodies that include vimentin, cytokeratins, and epithelial membrane antigen. However, the reliability of this panel is weakened by inconsistent staining patterns.

METHODS

Archival formalin fixed, paraffin embedded cell block sections from 45 FNAs of known primary and metastatic ACC and RCC as well as benign adrenocortical nodules were stained with anti-alpha-inhibin using an avidin-biotin procedure. All samples were microwave pretreated and a biotin block was performed to reduce the background stain due to the high endogenous biotin often present in these types of samples.

RESULTS

All cases of ACC (n = 7; 100%) and benign adrenocortical cells (n = 15; 100%) were immunoreactive with the a-inhibin antibody, showing a diffuse cytoplasmic and granular staining pattern. The staining intensity and number of immunoreactive cells varied within each sample, with the cases of ACC having the greatest proportion of immunoreactive cells and the strongest intensity. None of the cases of RCC (n = 23; 0%) were immunoreactive with anti-alpha-inhibin.

CONCLUSIONS

The morphologic distinction of ACC versus RCC in FNA material from renal, adrenal, and metastatic neoplasms is not always feasible based on cytology alone. However, due to the advent of the alpha-inhibin antibody, the reliable distinction of these entities now may be possible. The intense and specific immunostaining pattern for cells of adrenal origin, even in paucicellular samples, suggests potential for the widespread clinical utility of this marker by cytopathologists.

Transitional cell carcinoma arising in a pyelocaliceal cyst. An unusual cystic renal lesion with cytologic and imaging findings

The differentiation between benign and malignant cystic lesions of the kidney is a diagnostic challenge. Medical imaging aids in this task, but many cystic renal lesions require further work-up, frequently by computed tomography-guided fine needle aspiration. We report on the pathological findings in a case of moderately differentiated papillary transitional carcinoma, which arose in a pre-existing pyelocaliceal cyst in a 53-year-old man. In the case of this lesion, the distinction between a benign and a malignant renal cyst is blurred. To our knowledge, this is the third such occurrence to be reported and the first to be diagnosed by fine needle aspiration biopsy.

Diagnostic value of brush cytology in the diagnosis of duodenal, biliary, and ampullary neoplasms

Endoscopy is a valuable tool in the diagnosis and management of duodenal lesions and biliary strictures. We assessed the value of cytology in the evaluation of these lesions and analyzed the causes of discrepancy among clinical, histologic, and cytologic parameters. The study included 118 patients with duodenal ulcers, ampullary neoplasms, or biliary strictures who were examined between 1975 and 1995; 120 cytologic examinations were performed. The specimens included brushings of the duodenum (DB, n = 50), ampulla (AB, n = 32), and biliary ducts (BB, n = 38). Endoscopic biopsies performed concurrently included the duodenum (n = 37), the ampulla (n = 22), and the biliary ducts (n = 23). Comparison of cytologic and histologic results showed the following sensitivity and specificity: DB, 40% and 97%, respectively; AB, 100% each; BB, 75% and 93%, respectively. The DB, AB, and BB revealed malignant neoplasms in 2 of 5, 7 of 7, and 6 of 8 cases, respectively. Twenty-three duodenal neoplasms were diagnosed by either modality and included 11 adenocarcinomas, 9 villous tumors, 2 metastatic renal cell carcinomas, and 1 large cell non-Hodgkin's lymphoma. Endoscopic brush cytology is an effective means of diagnosing ampullary neoplasms, and it complements tissue biopsy in cases of bile duct stricture. Location, predominance of tumor-induced stroma, an extramucosal growth pattern, sampling error, and interpretative experience influence the diagnostic evaluation. Cytologic diagnosis of an adenoma does not exclude an underlying malignant neoplasm in ampullary tumors. In some instances, it may be difficult to distinguish between villous tumors with severe dysplasia and adenocarcinomas by cytology alone.

Aspiration cytology of malignant neoplasms associated with granulomas and granuloma-like features: diagnostic dilemmas

BACKGROUND

Malignant lymphomas and solid tumors that mimic or are associated with epithelioid granulomas are widely recognized in surgical pathology, but have received little attention in the cytopathology literature. In this study the authors present their experience with six such cases in which the presence of granulomas or granuloma-like features posed a diagnostic difficulty on fine-needle aspiration cytology (FNAC).

METHODS

Clinical data, FNAC, and follow-up surgical specimens from six patients presenting with neck masses were reviewed.

RESULTS

Only one case was diagnosed confidently as metastatic squamous cell carcinoma with an extensive granulomatous response; the other five were interpreted as "atypical" with descriptive cytology and a differential diagnoses including granulomatous inflammation, in addition to a caveat of "cannot exclude malignancy." Biopsy studies in these cases were recommended in view of the atypical cytologic findings and strong clinical suspicion of malignancy in each case. The histologic findings in two cases revealed Hodgkin's disease with exuberant granulomatous response. The remaining three cases were found to be malignant neoplasms with epithelioid morphologic features and included one example each of diffuse large cell lymphoma, anaplastic carcinoma of the thyroid, and lymphoepithelial carcinoma.

CONCLUSIONS

Malignancies associated with granulomas and tumor cells mimicking epithelioid histiocytes may be difficult to diagnose accurately on FNAC. The cytologic differential diagnosis of a "granulomatous" process should include malignant neoplasms. Excisional biopsy studies may be required for definitive diagnosis.

Diagnosis of infectious diseases: a cytopathologist's perspective

This review explores the role of the cytopathology laboratory in the detection and presumptive identification of microorganisms. Sample procurement by exfoliation, abrasion, and aspiration techniques, as well as a variety of cytopreparatory and staining methods, is reviewed. Emphasis is placed on the utility of fine-needle aspiration as a rapid, safe, and cost-effective diagnositic procedure. The role of rapid interpretation and specimen triage is also discussed. Cytomorphologic features and staining characteristics are presented for a spectrum of microorganisms potentially encountered in the cytopathology laboratory. Pitfalls in diagnosis and the usefulness of special stains and ancillary techniques are also evaluated. The importance of communication, collaboration, and clinical correlation is stressed.

Another quality assurance issue--amended reports: what do we really know about them?

The Clinical Laboratory Improvement Amendment (CLIA) of 1988 requires that if a cytology/histology discrepancy is discovered which is significant and affects patient care, an amended report should be issued (Clinical Laboratory Improvement Amendments, Fed Reg 1992;57:7169). Since little is known about such amended reports, a survey was developed to assess how individuals handle discrepancies. The Quality Assurance Task Force from the Papanicolaou Society of Cytopathology created a survey to assess these methods and sent it to all of their members. Fifty-one individuals responded to the survey. Methods vary widely among institutions. On average, 107 cytologic/histologic correlations are performed each month with the discovery of approximately 2 major and 11 minor discrepancies. Thirty-nine responders utilize written amended reports and telephone clinicians when a major discrepancy is found. Thirty-eight individuals indicated that their place of employment has a written policy concerning discrepancies. Time spent in quality assurance issues averaged 8 hr per wk for cytotechnologists and 3 hr per wk for pathologists. Although amended reports are required when significant discrepancies are revealed, a standard practice does not exist.

Diagnostic pitfalls of aspiration cytology of salivary duct carcinoma

BACKGROUND

Salivary duct carcinoma (SDC) is a highly aggressive primary salivary gland neoplasm that resembles intraductal and infiltrating breast carcinoma histologically. The purpose of this study was to review the cytologic features of histologically proven salivary duct carcinomas and to identify the potential pitfalls in cytologic diagnosis.

METHODS

Fine-needle aspiration cytology of nine histologically proven salivary duct carcinomas was reviewed.

RESULTS

The patients' age ranged from 62 to 89 years (median, 69 years). There were eight males and one female. The cytologic diagnoses of these cases were as follows: pleomorphic adenoma (PA) (three cases), high grade carcinoma, not otherwise specified (three cases), mucoepidermoid carcinoma (MEC) (two cases), and atypical cytology with differential diagnosis including MEC, oncocytoma, and acinic cell carcinoma (one case). The spectrum of cytologic findings included broad flat sheets and three-dimensional clusters. There was mild to severe cellular pleomorphism and nuclear atypia. Papillary clusters and cribriforming occasionally were identified. Bland cytologic features and prominent hyaline stroma, shown to represent the dense fibrosis on histologic sections, were identified in three cases cytologically interpreted as PA.

CONCLUSIONS

Fine-needle aspiration of SDC may be difficult to interpret accurately, and bland cytomorphologic features in some cases may lead to a false-negative interpretation; several clinically important pitfalls are demonstrated in our series.

Syncytial variant of nodular sclerosing Hodgkin's disease: fine-needle aspiration findings in two cases

The syncytial variant is a recently described, uncommon form of nodular sclerosing Hodgkin's disease that was previously termed "sarcomatoid." In addition to foci of typical sclerosis, it is characterized histologically by sheets or clusters of mononuclear Reed-Sternberg variants. These may be arranged around areas of necrosis with variable numbers of neutrophils. In excised material, differential diagnostic considerations include non-Hodgkin's malignant lymphoma, granulocytic sarcoma, malignant melanoma, metastatic carcinoma, thymoma, and metastatic germ cell tumor. We describe the fine-needle aspiration cytologic finding in two examples of this entity. Cohesive clusters and sheets of malignant cells with clear cytoplasm, vesicular nuclei, and prominent nucleoli are easily mistaken for metastatic carcinoma or germ cell tumor. Ancillary tests useful in this differential diagnosis are discussed.

Basaloid squamous carcinoma metastatic to renal-cell carcinoma: fine-needle aspiration cytology of tumor-to-tumor metastasis

We describe an unusual case of a basaloid squamous-cell carcinoma (BSCC) of the tonsil in a 56-yr-old man that metastasized to a primary renal-cell carcinoma (RCC) and the lung. The diagnosis of the second primary, the RCC, was based on fine-needle aspiration (FNA) cytology. A subsequent nephrectomy specimen revealed BSCC metastatic to RCC, clear-cell type. Retrospective analysis of the FNA of the renal mass revealed classic RCC morphology and, in addition, another cytologically distinctive pattern characterized by occasional sheets of cohesive neoplastic cells with hyperchromatic nuclei and nuclear molding representative of BSCC. The cytologic features of a subsequent FNA of the lung were characteristic of metastatic BSCC. Our retrospective analysis of cytologic material from the renal mass underscores the importance of raising the possibility of tumor-to-tumor metastasis when distinctly different morphologic features are seen in an otherwise typical cytology of a neoplasm in patients with an already known or suspected second primary. To our knowledge, this case report is the first one documenting metastasis of BSCC to RCC.

Spindle-cell lesions of the mediastinum: diagnosis by fine-needle aspiration biopsy

Spindle cells seen in fine-needle aspiration biopsy (FNAB) of the mediastinal lesions can be a component of a wide variety of benign and malignant conditions. Few of these conditions, however, are described in the FNA cytopathology literature. This review discusses the cytopathologic features, differential diagnoses, and potential pitfalls of a variety of lesions with a significant component of spindle cells encountered in mediastinal FNAB. The cytopathology files from four institutions were searched for cases of mediastinal FNAB containing a spindle-cell component that was a key or predominant cytologic feature of the diagnostic specimen. The cytomorphologic features of these cases were analyzed, and their differential features are discussed. Of 196 mediastinal FNABs, 22 (11%) were lesions with significant spindle-cell component: granulomatous inflammation (four); benign nerve sheath tumor (four); thymic cyst (two); spindle-cell thymoma (two); large-cell non-Hodgkin's lymphoma with sclerosis (two); nodular sclerosing Hodgkin's disease (two); liposarcoma (two); spindle-cell squamous carcinoma possibly arising in a teratoma (one); unspecified high-grade sarcoma (one); spindle-cell malignant melanoma (one); and nonspecific fibrous tissue (one). The cytologic features of each lesion were analyzed as an aid for accurate classification. These findings were correlated with radiologic and clinical information when available. The value of ancillary studies performed on aspirated material in selected cases was also reviewed. FNA of mediastinal lesions with significant spindle-cell morphology represents an infrequent and heterogeneous group of entities that may pose significant diagnostic challenges. This review presents the salient cytopathologic features of various spindle-cell lesions of the mediastinum with particular emphasis on differential diagnosis and pitfalls. The pathologist must use caution when interpreting these lesions and ancillary studies may be of significant value in selected cases.

Fine-needle aspiration cytopathology of malignant fibrous histiocytoma

BACKGROUND

Most pathologists generally accept malignant fibrous histiocytoma (MFH) as the most common soft tissue sarcoma in adults. This study examines the authors' aspiration cytopathology experience with this tumor, describes its cytomorphology, and determines the reliability of such a diagnosis by fine-needle aspiration biopsy (FNAB).

METHODS

The authors' files were reviewed for cases diagnosed as MFH by FNAB, and for surgical pathology cases of MFH previously aspirated but not diagnosed as such by cytology.

RESULTS

Fifty-two cases of MFH (by FNAB or histology) were recovered from the combined files; 42 aspirates had tissue confirmation. Patient age ranged from 15-88 years (mean, 63 years); the male:female ratio was 1.2. Thirty aspirates were from primary tumors, and 12 were from recurrences or metastases. From the 29 aspirates diagnosed as MFH, 24 (83%) were determined to be MFH on subsequent surgical excision. Four of the remaining cases were other sarcoma subtypes, and there was one organizing thrombus (false-positive). The remaining 13 aspirates were identified as unqualified sarcoma (11 cases) or a different sarcoma subtype (2 cases). Eleven of these were histologically diagnosed as MFH, and 2 as other sarcomas. No single cytologic feature or combination of features distinguished MFH. Patterns ranged from single cells to large storiform fragments. Spindled, plasmacytoid, and pleomorphic cell shapes were found; pleomorphic cells were often multinucleated. All cases of MFH had malignant nuclear morphology. Diagnostic pitfalls included low cellularity, obscuring blood and inflammation, and inadequate clinical and/or radiologic information.

CONCLUSIONS

The diagnostic role of FNAB in soft tissue lesions remains controversial. FNAB is important in the initial triage of patients with soft tissue tumors, and is particularly accurate for confirming recurrent or metastatic disease. Although making an initial diagnosis of sarcoma by FNAB is reliable, specific subtyping of them as MFH is more problematic.

Cytology of germ cell tumors: extragonadal, extracranial masses and intraoperative problems

BACKGROUND

Germ cell tumors (GCTs) and their metastases may be found in numerous sites that are accessible to cytologic sampling, and many are responsive to chemotherapy.

METHODS

The authors reviewed 20 examples of GCT cytology from 16 males and 3 females ranging in age from 1.5 to 61 years (median, 34 years). With two exceptions, one benign cystic ovarian teratoma in which intraoperative cytology was used to diagnose an associated adult-type carcinoma and one undescended testis in which seminoma presented as an abdominal mass, the material reviewed included no examples of primary gonadal GCT.

RESULTS

The authors studied 7 primary and 13 metastatic GCTs; these studies were based on 13 in vivo aspirations, 4 intraoperative preparations, and 3 samples of body cavity fluids. All samples were correctly interpreted as malignant, and only one was incorrectly classified as a non-GCT malignancy.

CONCLUSIONS

Clinical and cytologic findings are useful in the diagnosis of GCTs and their metastases. Incorrect interpretation of these neoplasms as poorly differentiated malignancies of other types may deprive the patient of effective chemotherapy. Air-dried, Romanowsky-stained smear material and cell block sections may contribute to the resolution of diagnostic dilemmas.

Diagnostic pitfalls in fine-needle aspiration biopsy of the mediastinum

A retrospective review of 189 fine-needle aspiration (FNA) biopsies of the mediastinum from four university medical centers was performed. Review of Diff-Quick- and Papanicolaou-stained direct smears was performed from a series of 189 FNA biopsies along with surgical pathology correlation obtained in 42% of the cases. There were 28 (14.8%) nondiagnostic or unsatisfactory for diagnosis cases. Of the satisfactory FNA specimens with histologic correlation, 12 cases (6%) were discordant. These errors primarily involve subclassification of small-cell malignancies involving the mediastinum, including a misdiagnosis of small-cell carcinoma for lymphoma. Large-cell lesions that were problematic included the accurate diagnosis of Hodgkin's lymphoma including the separation from non-Hodgkin's lymphoma. Large-cell lymphoma with sclerosis was misinterpreted in two cases due to distortion of cells by the mesenchymal tissue and sparsely cellular smears. In two cases classification of primary germ-cell tumors and separation from metastatic carcinoma was a problem. In general, FNA of the mediastinum is an accurate procedure, but can be challenging in a minority of cases due to sparse cellularity of the lesions and accurate classification of a variety of neoplasms that occur in this region. These 12 discordant cases serve as the basis of our report.

Cytologic diagnosis of peritoneal fluids. Applicability to the laparoscopic diagnosis of endometriosis

OBJECTIVE

To determine the accuracy of cytologic examination of laparoscopically obtained peritoneal fluid in the diagnosis of endometriosis.

STUDY DESIGN

This investigation analyzed 50 laparoscopic fluid specimens received over a three-year period. Retrospective cytologic findings were correlated with clinical history and laparoscopic diagnoses. Touch preparations were also collected from necropsies to develop cytologic criteria necessary to distinguish endometrial cells from mesothelial cells.

RESULTS

The presence of hemosiderin-laden macrophages in peritoneal fluids was more specific but less sensitive than the presence of endometrial cells for the diagnosis of endometriosis.

CONCLUSIONS

In women undergoing laparoscopy to detect endometriosis, the identification of endometrial cells alone in peritoneal fluids may not be sufficient to render a definitive diagnosis of endometriosis. However, the presence of hemosiderin-laden macrophages in this population should alert the cytologist to that possibility.

Fibromatosis colli. The utility of fine-needle aspiration in diagnosis

BACKGROUND

Fibromatosis colli (FC), also known as sternocleidomastoid tumor of infancy, is a benign spindle cell lesion of the sternocleidomastoid muscle. It usually is seen in the first few weeks of life and is the most common cause of a neck mass in the perinatal period. Although FC may lead to congenital muscular torticollis requiring surgical intervention, if the diagnosis of FC is certain, the usual initial treatment option is conservative management.

OBJECTIVE

To show the utility of fine-needle aspiration in the diagnosis of FC.

PATIENTS

Five cases in which fine-needle aspiration was used in the evaluation of patients with FC were identified retrospectively by a search of the cytopathology files of the State University of New York Health Science Center at Syracuse and the Virginia Commonwealth University, Medical College of Virginia, Richmond.

RESULTS

Fine-needle aspiration yielded an initial diagnosis of FC in 4 of the 5 cases. Smears made from the aspirated material were of low cellularity, but showed a characteristic population of spindle-cell fibroblasts. In addition to these fibroblasts, a variable amount of degenerating skeletal muscle was present in the background.

CONCLUSION

With the collaborative efforts of otolaryngologists and pathologists, fine-needle aspiration can be used to confirm a clinical diagnosis of FC while avoiding the expense and risk of open biopsy.

Basal cell (monomorphic) and minimally pleomorphic adenomas of the salivary glands. Distinction from the solid (anaplastic) type of adenoid cystic carcinoma in fine-needle aspiration

Cytologic features of the cell-stroma interface are useful in distinguishing between monomorphic adenomas of the basal cell type and adenoid cystic carcinoma. In basal cell adenomas, the collagenous stroma interdigitates with adjacent cells, whereas in adenoid cystic carcinoma, the two are separated by a sharp smooth border. Furthermore, the stroma of basal cell adenomas can contain rare spindle cells or capillaries, but the cylinders of adenoid cystic carcinoma are acellular. The authors review their experience with five cases of basal cell adenoma, and three cases that were designated "minimally pleomorphic adenomas." The latter group showed the small blue cell pattern of basal cell adenoma at the time of fine-needle aspiration, and histology revealed only small foci of typical pleomorphic adenoma. With the exception of one cystic case, the cell-stroma interface of basal cell adenoma was observed in all eight cases. These cases are contrasted with three adenoid cystic carcinomas with extensive solid (anaplastic) areas. All showed the small blue cell pattern and cell-stroma interface features of basal cell adenoma. Neither showed the smooth-bordered cylinders of adenoid cystic carcinoma. Two of these three were incorrectly interpreted as benign at the time of fine-needle aspiration. The authors suggest that the stroma aspirated from solid adenoid cystic carcinoma represents desmoplastic tumor stroma that mimics the pattern of basal cell adenoma in smear material. Distinction between basal cell adenoma and the solid type of adenoid cystic carcinoma at the time of fine-needle aspiration remains a very difficult problem.

Thymoma mimicking lymphoblastic lymphoma: a pitfall in fine-needle aspiration biopsy interpretation

Lymphocyte-rich thymoma often contains lymphoblasts and lymphoblastic lymphoma often infiltrates the thymus gland. Although these two neoplasms are clinically distinct in most case, their cytologic features may be similar on biopsy. We describe a fine-needle aspiration biopsy of a thymoma in a 50-yr-old man to increase awareness of this pitfall in cytologic interpretation.

Adenoid basal carcinoma of the cervix: a potential pitfall in cervicovaginal cytology

Adenoid basal carcinoma (ABC) of the cervix is a quite uncommon, indolent, yet invasive neoplasm rarely identified on cervicovaginal smears. This may be due in part to sampling. Unless ABCs become ulcerated, even vigorous brushing of the endocervical canal may not be adequate to dislodge the small, cohesive cells of this neoplasm. Fortunately, the association of ABC with squamous intraepithelial lesions (SIL) often results in its incidental diagnosis on follow-up cervical biopsy or endocervical curettage. We report two cases of ABC. In case 1, a 79-yr-old white woman was diagnosed with squamous-cell carcinoma on cervicovaginal (CV) smear. High-grade SIL, carcinoma in situ, and ABC were identified on subsequent cervical cone biopsy and hysterectomy. Retrospective evaluation of the CV smear revealed a few aggregates of small, uniform cells, with hyperchromatic nuclei representing fragments of ABC. In case 2, atypical basaloid cells suspicious for ABC were recognized on the CV smear of a 67-yr-old black woman, and ABC was subsequently confirmed on cervical cone biopsy. In neither case did the intervening cervical biopsy reveal ABC. In addition to a review of the clinical information useful in the diagnosis of ABC, the cytologic features of these two cases are compared with their subsequent histopathology and contrasted with other similar lesions comprising the differential diagnosis of small neoplastic cells found in cervicovaginal smears.

Exfoliative respiratory cytology in the diagnosis of leukemias and lymphomas in the lung

Leukemias and lymphomas involving the lung were diagnosed by means of exfoliative cytology in 31 specimens from 20 patients. Initial diagnostic categorizations included 29 specimens "positive for malignancy," including two thought to represent "carcinoma vs. lymphoma," and two considered suspicious for lymphoma. Previous diagnoses of lymphoma (13 patients) and acute myelogenous leukemia (AML) (2 patients) were available. In 5 additional patients, exfoliative respiratory cytology yielded the first diagnosis of hematopoietic malignancy. Cytologic diagnosis included nine large-cell and six small-cell non-Hodgkin's lymphomas (NHL), three Hodgkin's lymphomas (HD), and two AML. Key cytologic features included markedly pleomorphic and monomorphic cell populations in HD and NHL, respectively, as well as lack of tumor cell cohesion and necrosis in all cases. Cytologically, acute leukemia may be difficult to differentiate from large-cell NHL, and small-cell NHL from reactive/benign small lymphocytes. Blood, scant cellularity, crush artifacts, and apparent molding may affect diagnostic accuracy. Immunocytochemistry in cell block sections of sputa and washings is useful in the diagnostic workup in selected cases. Although involvement of the respiratory system by leukemias and lymphomas is uncommon and not always preceded by a history of malignancy, cytologic diagnosis is usually prompt, reliable, and accurate.

Fine-needle aspiration biopsy of the mediastinum. A multi-institutional analysis

The combined experience of four university medical centers with fine-needle aspiration biopsy (FNAB) of the mediastinum is reviewed. This series includes 189 cases, with 100 males and 89 females, 6 months to 86 years of age. The majority (71%) of diagnoses were neoplastic with the remainder equally distributed between nondiagnostic/unsatisfactory and nonneoplastic lesions. Malignant lymphoma and thymoma were the most frequent primary malignancies. Metastatic tumors represented the majority (60%) of neoplasms identified by FNAB. In 16% of these cases, the primary tumor was not identified. The majority (67%) of metastases were from the lung and were predominantly small cell type (52%). Sixty-six ancillary tests were performed on 51 cases (27%). Histologic correlation was available in 78 of 189 (41%) cases, with a diagnostic sensitivity and specificity of 87% to 88% for the detection of neoplasm and 82% to 83% for distinguishing benign from malignant disease. The positive predictive value for the presence of neoplasm was 97% with three cytologic false positives identified. This series is the largest to date on the utility of FNAB for lesions of the mediastinum.

"Cercariform" cells: a clue to the cytodiagnosis of transitional cell origin of metastatic neoplasms?

The "cercariform" cell is described as a distinct cytomorphologic clue that may be helpful in the diagnosis of metastatic transitional cell neoplasms, particularly low grade. This cell has a nucleated globular body and a cytoplasmic process with a nontapering, flattened, bulbous or fishtail-like end. The cercariform cell corresponds to intermediate cells in histologic and ultrastructural preparations of normal urothelium. The cercariform appearance is the result of pseudostratification of both normal and low-grade neoplastic urothelium. The unique features of cercariform cells make them readily distinguishable from neoplastic squamous cells as well as spindle cells of mesenchymal origin.

Primary and metastatic high-grade carcinomas of the salivary glands: a cytologic-histologic correlation study of twenty cases

We reviewed the clinical and fine-needle aspiration (FNA) findings in 20 patients with poorly differentiated carcinomas presenting initially as parotid or as submandibular masses. There were 11 primary tumors and nine metastatic malignancies in 14 males and six females ranging in age from 39 to 89 yr (median = 66). The tumor types included three primary carcinomas with oncocytic features, three additional cases of high-grade parotid carcinoma, one case of primary neuroendocrine carcinoma, two examples of malignant mixed tumor, one high-grade mucoepidermoid carcinoma, and a single example of malignant lymphoepithelial lesion. Six patients with metastatic carcinoma had previous diagnoses of malignancy. In the three remaining individuals, primary carcinomas of the lung (two cases), and an unknown primary site presented initially as parotid masses. Five examples of metastatic squamous cell carcinoma, one metastatic basal cell carcinoma, and two metastatic renal cell carcinomas were identified. One parotid lymphoepithelioma was interpreted cytologically as an atypical lymphoproliferative process suggestive of Hodgkin's disease. Nineteen cases (95%) were correctly classified as carcinoma at the time of FNA. High-grade carcinomas aspirated from the parotid may be primary, but are frequently metastatic to either the gland, or to an intraparotid lymph node. Our experience indicates that some metastatic carcinomas present at this site, without a previous history of malignancy. Distinguishing primary from metastatic lesions has important therapeutic implications.

Fine-needle aspiration biopsy: pitfalls in the diagnosis of spindle-cell lesions

Seven cases of spindle-cell proliferations in which fine-needle aspiration biopsy (FNAB) did not correlate with subsequent histology are presented. Three cases were considered low-grade sarcoma, one a dermatofibrosarcoma protuberans (DFSP), one a spindle-cell tumor with malignancy not excluded, and one a rhabdomyosarcoma vs. a fibrosarcoma. Two of the these three were histologically nodular fasciitis and one an inflammatory pseudotumor. Two cases were diagnosed cytologically as fibromatosis or nodular fasciitis (NF). One of these histologically was an intramuscular hemangioma, the other a DFSP. The last two cases were diagnosed by FNAB as spindle-cell lesion, undetermined if benign or malignant, and malignant fibrous histiocytoma (MFH). Histologically both of these case were leiomyosarcoma. The cytologic features of each case, differential diagnosis, and potential pitfalls are discussed. In the evaluation of FNAB smears dominated by spindle cells, cellullarity, individual cells and cell patterns, and background stromal features coupled with a precise clinical history may allow a narrow differential diagnosis with a focus on whether the lesion is benign or malignant. Caution is warranted in the exact classification of spindle-cell tumors from FNAB as this may have a major impact on patient management.

Fine-needle aspiration cytology of suture granulomas of the breast: a potential pitfall in the cytologic diagnosis of recurrent breast cancer

The fine-needle aspirates of three cases of suture granulomas of the breast area following mastectomy, lumpectomy, or axillary node dissection were reviewed. The original histologic diagnoses were mucinous (colloid) carcinoma, intraductal carcinoma, and low-grade phyllodes tumor. In two patients a new nodule developed in the surgical scar, and in the third a nodule developed in the axilla 2 cm away from the scar. The cellularity of the aspirates ranged from low to moderate, and all three cases contained variable numbers of spindled cells and fragments of cellular stroma. Multinucleated giant cells characteristic of suture granulomas were absent in all cases. Abundant metachromatic amorphous background material was present in one case, which was interpreted as recurrent mucinous carcinoma. The remaining cases were interpreted as suspicious for recurrent neoplasm. Upon excision, all were suture granulomas with fibroblastic proliferation. Suture granulomas can both clinically and cytologically mimic recurrent malignancy. The predominance of spindled cells and dissimilarity to the original tumor appear to be the most helpful features to cytologically distinguish suture granuloma from recurrent carcinoma in the absence of the characteristic multinucleated giant cells.

Herpesvirus mimics. A potential pitfall in endocervical brush specimens

The recent media focus on inadequacies in cervical smear collection and interpretation has resulted in improved collection methods, such as endocervical brushes, as well as closer scrutiny of morphologic criteria. However, endocervical cell artifacts may be associated with these endocervical brushes. Recently in our laboratory a case of reactive-atypical endocervical cells that resembled the cytologic changes associated with Herpes simplex virus (HSV) infection resulted in a false-positive diagnosis of HSV infection. Of 14,622 gynecologic specimens accessioned over 14 months, 459 cases with reactive endocervical cells and 117 with atypical endocervical cells were reported. These cases were reviewed by two independent observers with no knowledge of the prior diagnoses and were evaluated for four cytologic criteria considered diagnostic of HSV infection: multinucleation, margination of nuclear chromatin, ground glass chromatin and intranuclear inclusions. Nineteen cases were diagnostic/suggestive of HSV; 19 additional cases were identified as herpesvirus mimics. The original diagnoses, demographics, clinical data and method of collection were reviewed. In all but three cases an endocervical brush was the method of collection. Of the four criteria studied, only ground glass chromatin had both high sensitivity (95%) and specificity (95%). Intranuclear inclusions, while pathognomonic, had low sensitivity (42%). Altered endocervical cells that mimic herpesvirus are a potential pitfall in the diagnosis of HSV infection. Use of strict criteria, knowledge of the collection method and clinical history will avoid misdiagnosis.

Fine-needle aspiration biopsy: dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) represents a spectrum of mesenchymal spindle cell tumors that typically involve both dermis and subcutis. Presented herein are six cases of DFSP, four of which were initially diagnosed by FNAB. The cytologic features useful in the identification of this lesion on Papanicolaou- and Diff-Quik-stained smears are discussed. Chief among these are the storiform stromal fragments, presence of entrapped adipose tissue and the recognition of fibrohistiocytic spindle cells. The potential pitfalls and the differential diagnostic possibilities of spindle-cell lesions, particularly those of fibrohistiocytic origin are discussed.

Cytodiagnosis and comparison of nondecidualized and decidualized endometriosis of the abdominal wall. A report of two cases

We describe two cases of endometriosis of the abdominal wall occurring in young, multiparous women in which the diagnosis was made by fine needle aspiration biopsy. One case illustrates the cytologic features of non-decidualized endometriosis: a biphasic population of stromal and glandular cells. In contrast, the other case showed large, plump stromal cells in a distinctive myxoid background, creating a picture of decidualized endometriosis. The differential diagnoses of palpable masses in the abdominal wall and the importance of clinicopathologic correlation are discussed.

Occult metastatic mesothelioma--diagnosis by fine-needle aspiration. A case report

Fine-needle aspiration biopsy of an enlarged right axillary lymph node was performed on a 33-year-old woman with Ebstein's cardiac anomaly. Microscopic examination of the cytologic material revealed large discohesive cells with abundant pale cytoplasm, "ruffled" cytoplasmic borders, and prominent central nucleoli. Immunocytochemical analysis of the aspirate confirmed the mesothelial origin of these cells and prompted the diagnosis of metastatic mesothelioma. Autopsy examination revealed a large pericardial mesothelioma with metastases to mediastinal and axillary lymph nodes. This case report demonstrates the usefulness of fine-needle aspiration biopsy in the diagnosis of metastatic mesothelioma.

Immunocytochemical staining of fine-needle aspiration biopsies of the liver as a diagnostic tool for hepatocellular carcinoma

Fine-needle aspiration biopsy (FNAB) under ultrasonographic or computerized tomographic guidance is a useful diagnostic procedure for hepatic neoplasms. However, cytologic criteria alone may not allow for the distinction of hepatocellular carcinomas (HCC) from cholangiocarcinomas (CC) and metastatic adenocarcinomas (MA). In an effort to refine the FNAB diagnosis of hepatic malignancies, a panel of immunocytochemical stains was applied to aspiration specimens from primary and metastatic carcinomas in the liver. Anticytokeratin antibodies with different specificities (Cam 5.2 and AE1) were used in conjunction with antibodies to carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and alpha-1-antitrypsin (AAT). All HCC, CC, and MA were immunoreactive with the antikeratin antibody Cam 5.2. However, only three (15%) HCC were positive with AE1, in contrast to 100% of CC and MA. Antibodies to CEA and AFP were also helpful diagnostic aids, especially for the three HCC that were immunoreactive with AE1. Canalicular staining for CEA was present in 47% of HCC, but in none of the CC or MA. AFP positivity occurred in 45% of HCC, but only one CC and none of the MA. AAT was not a useful marker for HCC due to low sensitivity and specificity. Immunocytochemistry is an effective adjunct to the cytodiagnosis of malignant liver tumors sampled by FNAB.

Fine-needle aspiration cytology of an unusual primary lung tumor, chondrosarcoma: case report

A case of primary chondrosarcoma of the lung diagnosed by fine-needle aspiration biopsy (FNAB) cytology in a 78-yr-old male is presented. A mass detected on chest x-ray and defined by CT scan was subjected to a preoperative percutaneous fine-needle aspiration under fluoroscopic guidance. The distinctive cytologic features of pleomorphic cells nestled in lacunae surrounded by a chondromyxoid background resulted in a diagnosis of chondrosarcoma. The left upper lobectomy specimen confirmed the FNAB diagnosis and identified the tumor as arising from the left upper lobe bronchus.

Fine-needle aspiration of a solitary pulmonary nodule following treatment of metastatic giant-cell tumor of bone

Giant cell tumor (GCT) of bone is a local, variably aggressive neoplasm with high local recurrence and occasional pulmonary metastases. Radiographically guided fine-needle aspiration (FNA) plays a large role in establishing a tissue diagnosis of lung metastases prior to therapeutic intervention. We present a patient with histologically proven pulmonary metastases from a femoral grade II GCT. These lesions were obliterated with combination HT-CT (hyperthermia and chemotherapy). The patient subsequently developed another pulmonary nodule at a site previously occupied by a GCT metastatic deposit. Radiographically guided FNA revealed that this new lesion was an adenocarcinoma, apparently of pulmonary origin. We suggest that this second neoplasm arose within a scar that developed after HT-CT ablation of one of the metastases. Additional intriguing features of this case are the effective HT-CT therapy of GCT metastatic to lung and the extended temporal course (some 16 yr from initial diagnosis to death).

Fine-needle aspiration cytology of adrenal cryptococcosis: a case report

A case of adrenal cryptococcosis diagnosed by fine-needle aspiration biopsy cytology in a 58-yr-old man is presented. The organisms were easily seen with routine modified Wright stain (Diff-Quik) as variably sized yeasts, some with a brightly eosinophilic capsule. The diagnosis was confirmed with mucicarmine and silver stains. The identification of fungi with routine cytologic stains allows a rapid presumptive diagnosis of the infectious agent, collection of material for confirmatory special stains, and prompt initiation of therapy.

Fine needle aspiration biopsy of extramedullary plasma cell tumors

Fourteen fine needle aspiration (FNA) biopsies of extramedullary plasma cell tumors (PCT) from 11 patients were reviewed and correlated with histology in eight patients. This series comprised seven men and four women ranging in age from 46 to 83 yr (median 69 yr). Discrete masses were located in lymph nodes (three patients), pleura (one patient), soft tissues of the neck (two patients), thorax (six patients), axilla (one patient), and inguinal region (one patient). A spectrum of cytologic findings was demonstrated which led to the clinical confirmation of myeloma in four of 11 patients and of solitary plasmacytoma in two of 11 patients. In addition, FNA biopsies confirmed the presence of extramedullary disease in four of 11 patients with previously diagnosed myeloma. In another patient with a poorly differentiated plasma cell neoplasm, excisional biopsy was recommended to confirm the presence of a plasma cell tumor. Clinical follow-up was available on ten patients; of these, nine were treated with aggressive chemotherapy and, in five instances, additional radiotherapy. The 10th patient succumbed to infection prior to treatment. Nine of the ten patients were dead of disease 3 days to 4 yr following clinical diagnosis of a plasma cell dyscrasia. One patient (Case 1) was lost to follow-up after biopsy confirmation of plasmacytoma. The cytomorphologic appearance of neoplastic plasma cells in FNA of solitary masses necessitates clinical evaluation for bone marrow disease, i.e., myeloma.(ABSTRACT TRUNCATED AT 250 WORDS)

Metachronous soft-tissue masses in children and young adults with cancer: correlation of histology and aspiration cytology

We describe a series of 28 fine needle aspiration biopsies (FNAB) of soft tissue from 22 patients. Four patients had two separate FNABs, and one had three aspiration procedures. The patient population was limited to children and young adults (age range, 2 months to 29 years; mean, 16 years) who were known to have diverse forms of cancer, and who subsequently developed a mass in the peripheral soft tissues (including breast). The interval between the time of diagnosis of the primary malignant neoplasm and FNAB ranged from 1 day to 17 years (mean, 39 months). All FNAB diagnoses were confirmed by subsequent surgical open biopsy or clinical follow-up greater than 1 year. No complications occurred from the procedure. The cytomorphology is presented in selected cases and correlated with the patient's original tissue histopathology. Twenty aspirates were diagnosed as cytologically malignant, one as suspicious for malignancy. Seven were considered benign. None were unsatisfactory. One false-positive and no false-negative cytologic diagnoses were obtained. The overall accuracy of FNAB diagnoses was 96%, while sensitivity was 100% and specificity 88%. Sites of aspiration included soft tissues of the head and neck (seven cases), trunk (eight cases), breast (four cases), and extremities (nine cases). Malignant cytologic diagnoses included sarcoma (thirteen), seminoma (two), lymphoma/leukemia (two), melanoma (one), undifferentiated neoplasm (one), and neuroblastoma (one). Electron microscopy of aspirated cells was used to confirm the diagnosis in two cases. Fine needle aspiration biopsy of soft tissue masses from children and young adults with cancer demonstrates a high diagnostic accuracy, and its use is justified in this population.

Fine needle aspiration cytology of metastatic lymphoepithelioma. A case report

A case is presented of lymphoepithelioma (undifferentiated nasopharyngeal carcinoma) metastatic to the cervical lymph nodes in a 12-year-old boy for whom material was obtained by fine needle aspiration (FNA) for the primary diagnosis as well as for ancillary studies. Papanicolaou-stained smears demonstrated the characteristic cytopathologic features of Regaud-type lymphoepithelioma; the diagnosis was substantiated by immunocytochemical and electron microscopic studies. This report discusses the reliability and rapidity of FNA in definitively diagnosing undifferentiated metastatic malignancies as well as providing superior material for ancillary studies demanded by lesions with complicated and difficult differential diagnoses.

Selective inhibition of functional lymphocyte subpopulations by ribavirin

The present studies were designed to examine the effects of ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), a broad-spectrum antiviral agent, on the generation of murine antibody responses in vitro. Whereas primary and secondary sheep erythrocyte-specific, plaque-forming cell responses by normal murine spleen cells were enhanced by low concentrations of ribavirin (1 microgram per culture), they were strongly inhibited by higher concentrations of ribavirin (5 to 10 micrograms per culture). Both phenomena occurred with the greatest magnitude when spleen cells were exposed to ribavirin 48 to 72 h after culture initiation. Enhancement appeared to result from selective interference with suppressor T cells, since ribavirin failed to augment lipopolysaccharide-specific plaque-forming cell responses in T cell-depleted spleen cell cultures but inhibited concanavalin A-induced lymphocyte proliferation and suppressor T cell generation in cultures of normal spleen cells. The immunosuppressive properties of ribavirin were mediated by a direct antiproliferative effect and, at higher concentrations, a cytotoxic effect for B lymphocytes, since the drug inhibited plaque-forming cell responses in T cell-depleted spleen cell cultures, suppressed lipopolysaccharide-induced lymphocyte proliferation and reduced viable spleen cell recoveries.

Inhibition of murine plaque-forming cell responses in vivo by ribavirin

The effects of ribavirin, a potent inhibitor of RNA and DNA virus replication, on the generation of primary plaque-forming cell (PFC) responses in vivo has been investigated. Intraperitoneal administration of ribavirin 1 day after immunization of C3H/HeJ mice with sheep erythrocytes (SRBC) suppressed splenic IgM and IgG PFC responses by 60 to 90%. Primary IgM PFC responses of C3HeB/FeJ mice to bacterial lipopolysaccharides (LPS), a T-independent antigen, were also inhibited to a similar extent. Inhibition of splenic PFC responses, without significant reduction in nucleated cell recoveries, was dose dependent between 0.5 and 4 mg ribavirin. Varying the time of treatment determined that optimal inhibitory activity occurred when ribavirin was administered simultaneously or 1 day after antigen. Kinetic analysis of PFC responses in ribavirin-treated mice revealed that suppression did not result from a delay in development since reduced numbers of PFC were found at all times after immunization. Ribavirin-treatment after primary sensitization in vivo also impaired the capacity of spleen cells to develop secondary PFC responses in vitro, indicating that ribavirin also inhibited memory cell generation.

Inhibition of murine plaque-forming cell responses in vivo by ribavirin

The effects of ribavirin, a potent inhibitor of RNA and DNA virus replication, on the generation of primary plaque-forming cell (PFC) responses in vivo has been investigated. Intraperitoneal administration of ribavirin 1 day after immunization of C3H/HeJ mice with sheep erythrocytes (SRBC) suppressed splenic IgM and IgG PFC responses by 60 to 90%. Primary IgM PFC responses of C3HeB/FeJ mice to bacterial lipopolysaccharides (LPS), a T-independent antigen, were also inhibited to a similar extent. Inhibition of splenic PFC responses, without significant reduction in nucleated cell recoveries, was dose dependent between 0.5 and 4 mg ribavirin. Varying the time of treatment determined that optimal inhibitory activity occurred when ribavirin was administered simultaneously or 1 day after antigen. Kinetic analysis of PFC responses in ribavirin-treated mice revealed that suppression did not result from a delay in development since reduced numbers of PFC were found at all times after immunization. Ribavirin-treatment after primary sensitization in vivo also impaired the capacity of spleen cells to develop secondary PFC responses in vitro, indicating that ribavirin also inhibited memory cell generation.