Chorioretinitis and vitreitis due to Tropheryma whipplei after transplantation: case report and review.

Whipple's disease is a very rare chronic multisystemic bacterial disease characterized by diarrhea, malabsorption, fever, and polyarthritis. Ocular manifestations occur very rarely. Previous reports have suggested that the use of immunosuppressive drugs appears to accelerate or exacerbate the clinical course of Whipple's disease; however, the illness has yet to be reported in the setting of transplantation. Herein, we describe what we believe is the first reported case of Whipple's disease after transplantation. The patient is a 51-year-old woman who developed progressive visual floaters and blurring of vision 30 years after living-related kidney transplantation for an autosomal-dominant polycystic kidney disease. Her allograft was functioning well on maintenance immunosuppressive therapy with azathioprine and prednisone when she developed visual abnormalities. Transient weight loss, gastrointestinal symptoms, and migratory polyarthralgia predated the onset of ocular disease by several years. The diagnosis of Whipple's bilateral vitreitis and chorioretinitis was confirmed by polymerase chain reaction analysis demonstrating Tropheryma whipplei nucleic acid in vitreous fluid and peripheral blood sample as well as by demonstration of the bacilli by cytopathology. Intraocular vancomycin, intravenous ceftriaxone, and prolonged course of oral trimethoprim-sulfamethoxazole therapy led to clinical improvement and recovery of visual acuity.

Adenoid cystic carcinoma of the lacrimal gland is frequently characterized by MYB rearrangement.

PurposeAdenoid cystic carcinoma (ACC) represents ~10-15% of salivary neoplasms and almost universally exhibits a lethal clinical course. ACC is also known to occur in the lacrimal gland. ACC is characterized by its heterogeneous morphology and may demonstrate tubular, cribriform, and/or solid architectural patterns. Unfortunately, these histopathological features are not specific to ACC and can be seen in other salivary gland-type neoplasms, introducing a diagnostic dilemma. The discovery of fusion transcripts has revolutionized the diagnosis, surveillance, and treatment of epithelial malignancies. In several anatomic subsites ACC is frequently characterized by a fusion transcript involving genes MYB and NFIB; more specifically, t(6;9)(q22-23;p23-24). This study explores the incidence of MYB rearrangement in cases of lacrimal gland ACC using fluorescent in situ hybridization.Materials and methodsRetrospective clinical and histopathological review of 12 cases of lacrimal gland ACC seen at Mayo Clinic over a 25-year period (1990-2015) was performed. Demographic and clinical data were obtained from medical records. Surgical pathology archival material including H&E slides and immunostains was re-examined. Formalin-fixed paraffin-embedded material was further evaluated using immunohistochemistry when appropriate. Fluorescent in situ hybridization (FISH) using a MYB break-apart probe was applied to all histologically confirmed cases of ACC and benign salivary gland parenchyma.ResultsThe median patient age was 53.6 years (range 12-64) and distributed equally by gender (six male and six female). Rearrangement of MYB was identified using FISH in seven cases (58%). Twenty-five sections of benign salivary gland parenchyma showed no evidence of MYB rearrangement. Primary surgical resection was most common treatment, and 78% of the patient received adjuvant radiation therapy. Median overall survival (OS) was 11 years. Rearrangement of MYB did not affect OS.ConclusionsIn summary, our results indicate that the MYB rearrangement defines a significant subset of lacrimal gland ACCs. Importantly, FISH for MYB rearrangement may be used as a diagnostic tool during pathological examination of lacrimal gland neoplasms. Our results showed no relationship between rearrangement status and clinical outcome. Lastly, the presence of t(6;9) in ACC may provide a platform for molecular-targeting strategies in the future.

Plexiform fibrohistiocytic tumor with systemic metastases: a case report.

A case of plexiform fibrohistiocytic tumor with pulmonary metastases is presented. The tumor developed on the left wrist of a 4-year-old girl and metastasized to an axillary lymph node and lungs after an episode of local recurrence. This is the first report of systemic metastasis secondary to this neoplasm.

Paraneoplastic and metastatic neurologic complications of Merkel cell carcinoma.

Merkel cell carcinoma is a rare primary cutaneous neuroendocrine tumor that is locally aggressive and frequently accompanied by distant metastases. Neurologic complications of Merkel cell carcinoma are rare. We describe a 69-year-old man who presented with Lambert-Eaton myasthenic syndrome and was found to have Merkel cell carcinoma. The paraneoplastic syndrome improved with initial treatment of the malignancy. He subsequently developed a solitary brain metastasis and died of leptomeningeal carcinomatosis.

Laser pointers and the human eye: a clinicopathologic study.

We report the absence of photic retinal injury after exposing the retina to light from class 3A laser pointers for durations of up to 15 minutes. Three patients with uveal melanomas were scheduled to have an enucleation. Each agreed to have his or her retina exposed to laser light from a class 3A laser pointer prior to enucleation. Continuous exposure was directed to the fovea for 1 minute, to the retina 5 degrees below fixation for 5 minutes, and to the retina 5 degrees above fixation for 15 minutes. Ophthalmoscopic evaluation of the cornea, lens, and retina and fluorescein angiographic studies of the retina were conducted before, 24 hours after, and 11 days after laser exposure in the first case; before and 86 hours after exposure in the second case; and before, 96 hours after, and 15 days after exposure in the third case. Other than transient afterimages that lasted only a few minutes, we were unable to document any functional, ophthalmoscopic, fluorescein angiographic, or histologic evidence of damage to any structures of the eyes. Transmission electron microscopic studies of retinal sites targeted by the laser pointers in the second and third cases revealed ultrastructural abnormalities in the outer retina and the pigment epithelium that were similar to abnormalities seen in the retina approximately 8 mm away from the targeted sites. The risk to the human eye from transient exposure to light from commercially available class 3A laser pointers having powers of 1, 2, and 5 mW seems negligible.

Effect of clinical history on diagnostic accuracy in the cytologic interpretation of bronchial brush specimens.

There has been little study of the effect of clinical history on pathologic diagnostic accuracy. Five pathologists retrospectively examined 97 bronchial brush specimens with and without clinical historic information. Forty-nine patients had a biopsy-proven malignant lesion, and 48 had a benign lesion. Diagnostic accuracy with and without history for each pathologist was determined with likelihood ratios and receiver operating characteristic curves. The overall diagnostic accuracy with and without history was 0.84 and 0.76, respectively. The average negative predictive value of a benign diagnosis decreased from 89.2% (with history) to 74.0% (without history). Overall, the cytopathologists were more reluctant to make a definitive malignant diagnosis without history compared with history. The average positive predictive value of a malignant diagnosis with and without history was almost identical. The absence of history leads to lower diagnostic accuracy in the cytologic interpretation of bronchial brush specimens partly because pathologists underdiagnose malignant lesions.

Determination of silicon in breast and capsular tissue from patients with breast implants performed by inductively coupled plasma emission spectroscopy. Comparison with tissue histology.

A method for analysis of silicon in tissue was developed to determine silicon content in breast parenchymal and periprosthetic capsular tissues of patients with silicone or saline implants and to compare levels in tissues from normal (nonaugmented) breasts. It is of interest to determine whether increased silicon content in tissues can be associated with morbidity in patients who have received silicone implants. This manuscript addresses the issues involved in analysis of breast tissue samples for silicon and compares silicon levels with tissue histologic findings and patient morbidity. One hundred sixty tissue samples were obtained for silicon analysis from 72 patients during augmentation, capsulectomy with or without replacement mammoplasty, mastectomy, or biopsy procedures and were frozen in acid-washed polystyrene tubes at 220 degrees C until analysis. Samples were thawed, sectioned to approximately 0.1 g (dry weight), and digested in nitric acid before analysis by inductively coupled plasma emission spectroscopy, monitoring emission intensity at 251.6 nm. Tissue silicon levels (breast parenchymal and periprosthetic capsular tissue) in patients with silicone gel implants were much higher (mean, 9,287 micrograms/g, n = 106) than in patients with saline implants (mean, 196 micrograms/g, n = 37) or nonaugmented breasts (mean, 64 micrograms/g, n = 17). Histologic examination was performed on 54 tissue samples stained with hematoxylin-eosin. Tissue samples were rated as to degree of inflammation and calcification, and amount of giant cells, foamy histiocytes, and vacuoles containing a colorless refractory material. Vacuolization and foamy histiocyte ratings correlated significantly with tissue silicon concentration. No correlations were found between tissue silicon concentration and inflammation, calcification, or giant cell rating. Implant age (number of years an implant was in place before sampling) correlated with capsular tissue silicon concentration in patients with intact implants but not in those with ruptured implants. No difference in tissue silicon concentration was found between patients with or without signs or symptoms of morbidity. Using 0.1 g of tissue, the method was linear to 1,000 micrograms/g, and sensitivity was 3.7 micrograms/g. Precision between runs (mean, 5.1 micrograms/g; coefficient of variance, 13.7%; n = 13) was calculated from multiple analyses of a bovine liver standard (National Bureau of Standards, reference material 1577a). Significant biologic variability (21.4% to 52.5%) was seen in tissues with high silicon levels. Paraffin-embedded, formalin-fixed tissues are not amenable to silicon analysis by this method, because of leaching of silicone from the tissues during preparation. Thus only fresh frozen tissue samples were used.

Papillary thyroid cancer with pulmonary metastases in children: long-term prognosis.

BACKGROUND: Papillary thyroid cancer (PTC) in young patients may rarely be encountered with pulmonary metastases. Previous studies have suggested that, in the pediatric population, this may not portend a lethal outcome. Our present study, children with pulmonary metastases, was designed to clarify this issue. METHODS: Fourteen children and young adolescents (mean age, 13.5 years; range, 9.8-17 years) with PTC and pulmonary metastases were treated at our institution between 1937 and 1998. Surgical treatment consisted of total thyroidectomy (n = 10 patients), subtotal thyroidectomy (n = 3 patients), and a biopsy only procedure (n = 1 patient). All patients who underwent thyroidectomy also underwent a variety of cervical lymph node dissections, and all patients proved to have regional nodal disease. After the operation, 12 patients were treated with ablative doses of (131)I, 1 patient was treated with external beam irradiation, and all patients were placed on suppressive thyroid hormone therapy. The mean length of follow-up was 19.3 years (range, 1-45 years). RESULTS: Regional recurrent disease developed in 2 patients (15%). No patient experienced the development of worsening pulmonary disease or extra-pulmonary metastases. All patients with recurrent disease underwent selective nodal resections. No patient died of metastatic PTC. Seven patients (50%) remain completely free of disease and are probably cured; 7 patients (50%) are asymptomatic with residual pulmonary disease. CONCLUSIONS: A stepwise treatment approach allows long-term survival and frequent cure for young patients with PTC and concomitant pulmonary metastases.

Myofibroblastoma and solitary fibrous tumour of the breast: histopathologic and immunohistochemical studies.

Thirteen mesenchymal tumours of the breast were reviewed histologically and immunohistochemically. Nine tumours (male:female ratio 5:4, average age 64 years) were classified as myofibroblastomas and presented as a single nodule (four) or a multilobular mass (five). They were composed of elongated cells with vesicular nuclei showing grooves, intranuclear inclusion, and small but conspicuous nucleoli resembling myofibroblasts seen in scar tissue. In six tumours, hypercellular zones alternated with paucicellular, hyalinized areas. The collagen pattern was dense, diffuse, and brightly eosinophilic in all neoplasms. The tumour cells were positive for desmin, actin, and vimentin in all nine lesions, and in six tumours a focal CD 34 positivity was also demonstrated. Four tumours (four female patients, average age 75 years) were classified as solitary fibrous tumours and consisted of well-circumscribed nodules. They were characterized by a monomorphic population of thin, spindled to ovoid cells with finely dispersed chromatin and inconspicuous nucleoli. The pattern of the collagen in these tumours was one of thick, brightly eosinophilic bands. These four tumours were negative for all markers tested except vimentin and CD 34. Although myofibroblastomas and solitary fibrous tumours of the breast share many morphologic features, there are enough differences in their cytologic composition and, most importantly, in their immunohistochemical profile to consider them as distinct entities.

Microvascular invasion in prostate cancer correlates with pathologic stage.

OBJECTIVE: To determine the incidence of microvascular invasion in prostatic carcinoma and its correlation with other prognostic factors. DESIGN: Evaluation of the frequency and extent of microvascular invasion by routine light microscopy in 210 whole-mounted radical prostatectomies with cancer. RESULTS: Microvascular invasion was identified in 111 (53%) of 210 specimens. Focal microvascular invasion (involvement of fewer than three high-power fields) was present in 42 cases (20%); extensive microvascular invasion (involvement of three or more high-power fields) was present in 69 cases (33%). Capsular perforation was present in 43% and 62% of cases with focal and extensive microvascular invasion, respectively. Seminal vesical involvement was observed in 23% and 47% of cases with focal and extensive microvascular invasion, respectively. Lymph node metastases were only observed in cases with microvascular invasion and were present in 7% and 23% of cases with focal and extensive invasion, respectively. There was also a strong positive correlation of microvascular invasion with surgical margin status, Gleason score, and cancer volume. Tumors ranged in volume from 0.14 cc to 47.25 cc (mean, 9.09 cc), and the volume in cases without microvascular invasion was lower than in those with invasion (mean, 5.4 cc and 12.7 cc, respectively); also, the volume in cases with focal invasion was lower than in those with extensive invasion (mean, 9.4 cc and 16.1 cc, respectively). CONCLUSIONS: Microvascular invasion in prostatic carcinoma correlates positively with virtually all measures of pathologic stage. Its presence should be reported in all prostate specimens according to the Cancer Committee of the College of Americans Pathologists.

Hepatocellular carcinoma: needle biopsy findings in 74 cases.

Needle aspiration specimens from 74 cases of hepatocellular carcinoma (HCC) diagnosed between January 1986 and December 1992 were reviewed and compared with 57 other lesions. The most specific cytologic findings for HCC included capillaries separating tumor cells (34%), bile associated with malignant cells (19%), and endothelial cells lining clusters of neoplastic cells (18%). Less specific findings included polygonal cells with central nuclei resembling normal hepatocytes and intranuclear inclusions. Tissue core fragments available in 53 cases of HCC disclosed that a weak keratin (AE1/AE3) stain (75% of HCC), a canalicular pattern of polyclonal carcinoembryonic antigen (54%), and a positive alpha-fetoprotein stain (58%) are diagnostic of HCC. All HCCs were negative for monoclonal carcinoembryonic antigen. In situ hybridization for albumin mRNA was positive in 27 of 33 cases of HCC. The diagnosis of HCC by needle biopsy should include cytologic findings and the appropriate immunohistochemical profile, along with detection of albumin mRNA by in situ hybridization.

Cellular schwannoma mimics a sarcoma: an example of a potential pitfall in aspiration cytodiagnosis.

Cellular schwannoma, a variant of benign schwannoma, is characterized by marked nuclear pleomorphism and hyperchromasia and may be overdiagnosed as a malignancy in fine-needle aspiration specimens. We report the aspiration cytology findings of a case of cellular schwannoma that arose in the parapharyngeal region of a 50-yr-old woman.

Fine-needle aspiration cytology of esophageal leiomyomatosis.

Leiomyomata are the most common benign neoplasms of the esophagus, but they are still very rare in comparison to malignant tumors of this organ. We report on the aspiration cytology findings of a case of esophageal leiomyomatosis in a 19-yr-old man. Diagn. Cytopathol. 1999;21:197-199.

Solitary fibrous tumor: a study of cytologic features of six cases diagnosed by fine-needle aspiration.

Solitary fibrous tumor (SFT) is a spindle-cell neoplasm most often presenting as a pleural-based tumor but increasingly recognized in other locations. Few reports have described the cytologic features of SFTs. Six cases of SFT diagnosed by fine-needle aspiration (3 pleura, 2 retroperitoneum, and 1 orbit) were identified in the Mayo Clinic files. The smears (Papanicolaou-stained) and corresponding histologic specimens were reviewed. Immunohistochemical staining for CD34 was performed in all cases. The cytologic findings were similar in all cases. The tumor cells were oval to polygonal, with cellularity ranging from scant to moderate. The background contained irregular ropy fragments of collagen and a few inflammatory cells. Most cells were dispersed singly, but all cases contained irregular, loose aggregates of cells enmeshed in a collagenous matrix. The nuclei were uniformly bland, with evenly distributed, finely granular chromatin. All cases were immunoreactive for CD34. SFT has distinctive cytologic features that allow diagnosis in cytologic specimens with the help of appropriate immunocytochemical stains on accompanying tissue biopsy specimens. Distinctive cytologic findings predictive of clinical behavior were not identified.

Immunoglobulin G4-related disease of the orbit: imaging features in 27 patients.

BACKGROUND AND PURPOSE: Immunoglobulin G4-related disease is a systemic fibroinflammatory process of unknown etiology, characterized by tissue infiltration by immunoglobulin G4 plasma cells. The purpose of this study was to retrospectively identify the spectrum of imaging features seen in immunoglobulin G4-related disease of the orbit. MATERIALS AND METHODS: This study included 27 patients with biopsy-proved immunoglobulin G4-related disease of the orbit and either a CT or MR imaging of the orbits. These CT or MR imaging examinations were evaluated for the following: extraocular muscle size, extraocular muscle tendon enlargement, lacrimal gland enlargement, infiltrative process in the orbital fat (increased attenuation on CT or abnormal signal on MR imaging), infraorbital nerve enlargement, mucosal thickening in the paranasal sinuses, and extension of orbital findings intracranially. RESULTS: Extraocular muscles were enlarged in 24 of 27 (89%) patients, 21 (88%) bilaterally. In 32 of 45 (71%) affected orbits, the lateral rectus was the most enlarged muscle. In 26 (96%) patients, the tendons of the extraocular muscles were spared. Nineteen (70%) patients had lacrimal gland enlargement. Twelve (44%) patients had an infiltrative process within the orbital fat. Infraorbital nerve enlargement was seen in 8 (30%) patients. Twenty-four (89%) patients had sinus disease. Cavernous sinus or Meckel cave extension was seen in 3 (11%) patients. CONCLUSIONS: In patients with extraocular muscle enlargement, particularly when the tendons are spared and the lateral rectus is the most enlarged, and even more so when other noted findings are present, immunoglobulin G4-related disease should be a leading differential consideration, even over more commonly known etiologies of extraocular muscle enlargement.

Dermal and conjunctival melanocytic proliferations in diffuse uveal melanocytic proliferation.

AIM: The goal of this case report is to describe the dermatologic and conjunctival findings in a case of bilateral diffuse uveal melanocytic proliferation (BDUMP), a paraneoplastic syndrome usually associated with gynecologic cancers. There is little information about other dermatologic melanocytic findings in these patients. METHODS: Histologic and fluorescent in situ hybridization (FISH) analysis of three separate skin biopsies, one of which was separated by 21 months from the others, were performed in a 71-year-old patient with BDUMP to assess for histologic and chromosomal abnormality. Conjunctival histologic evaluation was also done. RESULTS: Dermal melanocytic proliferation was seen in each specimen. The cells were spindle type with mitotic activity. FISH analysis showed a normal copy of chromosomes. The conjunctival sample also showed normal FISH analysis. CONCLUSION: BDUMP is associated with multifocal dermal and conjunctival melanocytic proliferation.

Intraocular use of rituximab.

PURPOSE: To evaluate the toxicity of 1 mg of intraocular rituximab and to present a small case-series of patients treated with intravitreal rituximab. METHODS: Rituximab (1 mg/0.1 ml) was injected in the vitreous of one eye of three Dutch-belted rabbits. Two animals were injected with balanced salt solution as controls. At 1 month the rabbits were killed and the eyes examined by light microscopy. Three patients (five eyes) with intraocular lymphoma were also treated with a 1 mg injection of rituximab. RESULTS: The treated rabbit eyes and the control eyes showed no light microscopic evidence of ocular toxicity at 1 month following injection. The five human eyes of three patients have shown no evidence of intraocular toxicity with a median follow-up time of 3.6 months (range 2.0-6.4 months). One patient received a total of four injections in the right eye and three injections in the left eye. CONCLUSION: Intravitreal rituximab at a dose of 1 mg does not appear to cause toxicity in rabbit eyes and in the five eyes of three patients.

Cytologic changes in the conjunctiva mimicking malignancy after topical mitomycin C chemotherapy.

PURPOSE: To describe the epithelial changes observed in the conjunctiva secondary to the use of topical mitomycin C (MMC) for treatment of primary acquired melanosis with atypia. DESIGN: Retrospective comparative case series. PARTICIPANTS AND CONTROLS: Conjunctival biopsy specimens (18) were taken during the follow-up of ten patients treated with MMC drops (0.02% or 0.04%) during 14 or 21 days for primary acquired melanosis with atypia. An equal number of age- and sex-matched patients with normal conjunctival biopsy findings were included for control. Conjunctival biopsy specimens from patients treated with MMC were compared with the morphologic changes already described in the urothelium following the use of the same chemotherapeutic agent. METHODS: Hematoxylin and eosin-stained biopsy samples were evaluated for recurrent neoplasm and chemotherapeutic effect in the epithelium using the following criteria: nuclear enlargement, nuclear hyperchromasia, smudging of the chromatin, presence of nucleoli, cytoplasmic eosinophilia, and individual cell necrosis. MAIN OUTCOME MEASURES: The presence or absence of morphologic changes in the conjunctival epithelium related to the use of MMC. RESULTS: Morphologic features consistent with chemotherapy effect were seen in the biopsy specimens of nine patients. Nuclear enlargement and chromatin smudging-hyperchromasia localized in the superficial layers of the epithelium were the main features observed (9 patients). Cytoplasmic eosinophilia, single cell necrosis, and occasionally subepithelial chronic inflammation were also seen. CONCLUSIONS: Secondary changes with the topical use of MMC are seen in the conjunctival epithelium and are similar to the changes described in the urothelium. These changes are important to recognize and to differentiate from recurrent neoplasm. The localization of the described features in the superficial layers of the conjunctival epithelium is the key feature in the differential diagnosis.

Small cells in cervical-vaginal smears of patients treated with tamoxifen.

BACKGROUND: "Small cells" have been described in the cervical-vaginal (Papanicolaou [Pap]) smears of patients receiving tamoxifen. The current study determined the frequency of this finding and its implications for the differential diagnosis. METHODS: A computer-based search of the cytopathology files from January 1994 to December 1998 was performed for Pap smears from patients with a history of tamoxifen treatment. All smears were reviewed for the presence of "small cells" and endometrial cells. Pap smears from an age-matched control group that was not treated with tamoxifen also were screened for "small cells." RESULTS: Five hundred forty-eight Pap smears were identified from 425 patients (mean age, 62 years; average duration of treatment, 43 months). Clusters of these "small cells" were present in 104 Pap smears from 86 patients (19%). The background pattern was proliferative in the majority of the Pap smears (83%). In five Pap smears (5%), these "small cells" were interpreted originally as endometrial cells. In the remaining Pap smears, no reference to the presence of the cells was made in the original report. "Small cells" were identified in 79 Pap smears (18%) in the control group (n = 443 smears). CONCLUSIONS: The incidence of "small cells" is similar in the Pap smears of patients with or without a history of tamoxifen treatment. These cells are similar to reserve cells noted in atrophic smears. However, as a result of the proliferative effect of tamoxifen in the cervical epithelium, these cells are prominent when admixed with superficial and intermediate cells in patients treated with tamoxifen. These cells need to be differentiated from endometrial cells to avoid unnecessary follow-up procedures. Cancer (Cancer Cytopathol)

Rhabdomyosarcoma presenting as a parotid gland mass in pediatric patients: fine-needle aspiration biopsy findings.

BACKGROUND: The head and neck region is one of the most common locations of rhabdomyosarcoma. Salivary gland involvement is usually secondary to advanced disease, and presentation as a primary salivary gland tumor is very rare. METHODS: Three cases of rhabdomyosarcoma presenting as parotid masses, in 2 boys (ages 3 and 7 years) and a girl (age 5 years), were retrieved from the files of 2 institutions. RESULTS: The three patients presented with parotid gland enlargement. Clinically, the enlargements appeared to be inflammatory, and they were treated unsuccessfully with antibiotics. Fine-needle aspiration biopsy (FNAB) was performed on all three patients. The cytologic features varied from one case to another; one case had features of a small round cell tumor, another was composed of a monomorphic population of spindle cells in a metachromatic stroma, and the third case was composed mostly of spindle cells with moderate cellular pleomorphism. Immunohistochemical studies performed in two of the cases confirmed the diagnosis of rhabdomyosarcoma, and ultrastructural studies were confirmatory in the other case. The patients are alive; 2 of them have had no evidence of disease after 6 and 9 years of follow-up, and the third, the most recent patient, has just finished adjuvant chemotherapy. CONCLUSIONS: With the increased use of FNAB for the evaluation of salivary gland masses in children, the authors believe that it is important to recognize the occurrence of rhabdomyosarcoma in this location. Immunohistochemical studies have proved helpful in differentiating rhabdomyosarcoma from other parotid gland tumors and can be readily done on cytologic preparations.