Phyllodes tumor of the breast. A cytohistologic study of 80 cases

OBJECTIVE: To study the cytologic features of phyllodes tumor (PT) of the breast and determine the accuracy of their subclassification in fine needle aspirates. STUDY DESIGN: Eighty cases of histologically diagnosed PT between 1982 and 1997 with a previous fine needle aspiration (FNA) were evaluated. The FNA smears of each case were reviewed without knowledge of the initial cytologic diagnosis and subclassified into benign, borderline or malignant PT. RESULTS: Benign PTs were characterized by a dimorphic mixture of stromal and epithelial cells. The stromal fragments showed mild to moderate cellularity with absent to minimal pleomorphism and no mitosis. There were occasional, if any, single stromal cells. Borderline PTs had stromal fragments with moderately cellular stroma exhibiting moderate pleomorphism. Two additional features were the presence of single stromal cells and an occasional mitosis in the stromal fragments/single cells. Aspirates from malignant PT were very cellular, with a high stromal/epithelial ratio and marked stromal cellularity. The stromal cells were highly pleomorphic, with frequent mitosis and atypical single stromal cells in the background. Fifty-seven of the 80 histologically documented cases (71.3%) were diagnosed as PT on FNA (40 benign, 10 borderline and 7 malignant). In 81% (46 of 57 PTs), good cytohistologic correlation (32 benign, 8 borderline and 6 malignant) was observed. In another eight cases, one grade differentiation between cytologic and histologic grade was observed. Six of the nine malignant PTs on histology were correctly subclassified on cytology. There were one false positive and two false negative cases. CONCLUSION: Cytologic diagnosis and grading of PT on FNA is possible. Special care should be undertaken in interpreting phyllodes fragments, cellularity of stroma, pleomorphism and mitosis. Single stromal cells are also important morphologic criteria for subclassification. Multiple-site aspiration is advisable to avoid diagnostic errors.     

Evaluation of fine needle aspiration of the male breast for the diagnosis of gynaecomastia

Fine needle aspiration of the male breast can present problems of diagnosis because the cytological presentation of gynaecomastia can be confused with that of adenocarcinoma. We reviewed breast aspirates from 24 male patients in order to determine the accuracy of cytology as a method of diagnosing gynaecomastia. Discrepancies were observed between the original cytology reports on one hand and the review cytology and biopsies on the other. Of the 24 aspirates from the male breast, the cytology was reported as negative in 16 cases, suspicious in three cases and malignant in five. In four cases of the negative group, a specific diagnosis of gynaecomastia was made. In two of the negative cases the subsequent biopsies revealed adenocarcinoma. Of the five cases reported on the original cytology as adenocarcinoma, two on review showed the features of florid gynaecomastia and this was confirmed on biopsy and three confirmed the initial diagnosis of adenocarcinoma. The cytological features of gynaecomastia which distinguish it from adenocarcinoma are discussed.     

Cytomorphology of lipomatous tumors of soft tissue

OBJECTIVE: To evaluate the cytomorphologic features of benign and malignant lipomatous tumors of soft tissue on fine needle aspirates (FNA) and determine if the variants of liposarcoma could be identified. STUDY DESIGN: FNA of histologically documented benign (51 cases) and malignant (39 cases) lipomatous tumors were reviewed. Twenty-six of the 51 FNA from lipomas and 34 of the 39 FNA from malignant lipomatous tumors were satisfactory for evaluation. RESULTS: FNA from 26 cases of lipomas were cellular, with lobulated, fibroadipose tissue. Thin and thick capillaries were seen in 92% and 65% of cases, though a chicken wire vascular pattern was seen in only 4 cases (15%). A cytodiagnosis of liposarcoma could be made in 23 cases (88%), and these could be further subtyped into well-differentiated (4 cases), myxoid (8), pleomorphic (4), round cell (3) and liposarcoma, ?type (4). Only 50% of the well-differentiated liposarcomas, 3 of the 10 pleomorphic liposarcomas and 8 of the 17 myxoid liposarcomas were diagnosed as such on FNA. Cytologic diagnosis of the remaining 9 cases of myxoid liposarcoma were pleomorphic liposarcoma (1); liposarcoma, ?type (3); malignant mesenchymal tumor (1); suspicious for malignancy (2); and benign (2). There were no false positives, but there were 3 false negative cases (1 well-differentiated and 2 myxoid liposarcoma). CONCLUSION: Lipomas can be diagnosed readily. Arborizing vessels can be seen in lipomas and should be interpreted with caution. Subclassification of liposarcomas on FNA is possible but not very reliable. Myxoid liposarcomas pose a problem, and aspirates from them can mimic a wide range of morphologic subtypes. The role of FNA in identification of variants of liposarcoma is limited.     

The role of fine needle aspiration cytology in the diagnosis of lymphoma

The accuracy of fine needle aspiration (FNA) cytology for the diagnosis of lymphoma and other hematolymphoid malignancies was investigated by a review of 158 FNA specimens from 143 patients. Patients included in the study had either a diagnosis of a hematolymphoid malignancy by FNA cytology or a biopsy diagnosis of lymphoma that was preceded by FNA cytology. Biopsy specimens were obtained from 85% of the patients. Of the 158 needle aspirates, 118 (75%) were diagnosed as lymphoma, 13 (8%) as suspicious of lymphoma, 8 (5%) as myelomas, 3 (2%) as leukemias, 12 (8%) as positive for malignancy and 4 (2%) as negative for malignancy. Two of the 118 needle aspirates diagnosed as lymphoma were false positives while 3 of 13 diagnosed as suspicious for lymphoma were found to be benign. Overall, there were four false negatives. Morphologic subclassification of the lymphomas, originally attempted for 60 needle aspirates, was identical to the histologic subclassification in 51 cases (85%). FNA cytology provided the initial diagnosis of a hematolymphoid malignancy in 51% of the cases and allowed the documentation of recurrent disease in 49%. The results demonstrate the usefulness of FNA cytology for the diagnosis and management of patients with lymphoma.     

Fine needle aspiration cytology of solitary fibrous tumours of the pleura

OBJECTIVE: To analyse fine needle aspirates from solitary fibrous tumour (SFT) of the pleura and to elucidate the cytological features unique to these tumours and differential diagnostic findings of benign and malignant SFTs. METHODS: Fine needle aspiration (FNA) cytology slides from eight cases of SFT of the pleura, including six benign and two malignant SFTs, were reviewed. The subsequent histological slides were also examined. RESULTS: Cytological diagnoses from six histologically proven cases of benign SFTs were low-grade sarcoma (one), non-small cell carcinoma (one), malignant tumour (1) and benign (three). Two cases of malignant SFTs were cytologically diagnosed as malignancy. The aspirates showed a varying degree of cellularity. Most smears were composed of single, scattered fusiform cells, and irregular loose aggregates of oval to spindle cells intimately admixed with dense collagenous stroma. Two malignant SFTs had a greater number of cells in clusters, and displayed mitotic activity, without significant cytological atypia. CONCLUSIONS: The diagnosis of SFT may be suggested by a combination of cytological and radiological findings. The precise determination of malignancy for SFT, however, is not usually straightforward on the basis of cytological features alone. The findings of highly cellular clusters and mitotic activity in the FNA cytological smear can help differentiate malignant from benign SFTs.     

Papillary thyroid carcinoma with exuberant nodular fasciitis-like stroma in a fine needle aspirate. A case report

BACKGROUND: Papillary thyroid carcinoma (PTC) with exuberant nodular fasciitis-like stroma (PTC-ES) is a new morphologic variant of conventional PTC. It is characterized by extensive reactive stromal proliferation, which may occupy 60-80% of the tumor. CASE: A 42-year-old female developed a tender, left-sided thyroid mass. The fine needle aspiration biopsy specimen contained, besides diagnostic epithelial features of PTC, many cohesive tissue fragments of cellular stroma. CONCLUSION: A correct cytopathologic diagnosis of PTC-ES can be established if both epithelial and stromal components are present in needle aspirates.     

Diagnostic pitfalls in the fine needle aspiration of thyroid nodules. A study of 555 cases in Chinese patients

The diagnostic value and limitations of fine needle aspiration (FNA) were determined by examining 555 palpable thyroid nodules in Chinese patients who had a definitive diagnosis established by thyroidectomy (529 cases) or large-needle biopsy (26 cases). Of the aspirates, 97.8% were satisfactory for cytologic examination. The overall malignancy rate was 20%. FNA detected 73 (74.5%) of 98 primary malignant tumors and 9 (90%) of 10 metastatic tumors. Diagnostic errors were most commonly due to inadequate specimens and cystic lesions. Cystic fluid, present in one-third of all lesions, was associated with a malignant nodule in 13% of the cases. FNA was most valuable for detecting papillary carcinomas; it may at times suggest the likelihood of a follicular carcinoma.     

Semi-quantitative analysis of soft-tissue reactions in fine needle aspirates from tissue cysticercosis

Fine needle aspiration cytology (FNA) has a well-documented role in the diagnosis of cysticercosis. However, little is discussed about the associated inflammatory response in the host tissues. Aspirates from 182 cases of subcutaneous cysticercosis were semiquantitated for the type and degree of inflammatory response, and the amount and preservation of the parasite. Tissue sections were reviewed where available. In the FNA where no parasite was observed but a confirmatory tissue diagnosis was available, it was found that eosinophils (52%), epithelioid cell granulomas (30%), palisading histiocytes (33%) and giant cells (28%) were seen less frequently than in those where larval fragments were identified in the aspirated material in varying quantities, the response being 88-92% eosinophils, 50-70% palisading histiocytes, 68-80% epithelioid cell granulomas and 46-74% giant cells. Repair cells were maximally seen when readily identifiable larval fragments were seen in the aspirate. Bizarre cells were equally distributed in these aspirates. The tissue response in FNA from subcutaneous cysticercosis can be varied and eosinophils are found to increase with the presence of the degenerating parasite. In soft-tissue aspirates, palisading histiocytes with epithelioid cell granulomas with or without giant cells and an inflammatory exudate with predominantly eosinophils alerts one to search diligently for a parasite.     

Diagnosis of pancreatic carcinoma by fine needle aspiration cytology and computerized cytomorphometry

Eighty-one fine needle aspirations (FNAs) of pancreatic masses were performed between 1980 and 1988. Histologic or clinical follow-up was available for correlation with 78 aspirates. The FNA cytologic diagnosis of pancreatic carcinoma had a sensitivity of 79% and a specificity of 91%. Fifteen of the FNA specimens were examined with the Zeiss IBAS image analysis system to determine nuclear area, form (shape), diameter, density and integrated optical density (IOD). Nuclear area and IOD correlated most highly with the final diagnoses. Negative aspirates from benign cases and "false negatives" from malignant cases had similar morphometric values. Cells from adenocarcinoma had greater nuclear area and IOD values in cases cytologically labeled positive than in cytologically suspicious cases. Diagnoses based upon IOD values had a sensitivity and a specificity of 100% and 86%, respectively, while the use of nuclear area measurements produced values of 100% and 100%, respectively. These data indicate that nuclear area and IOD measurements can be valuable adjuncts to qualitative cytology for the diagnosis of pancreatic fine needle aspirates.     

Cytologic diagnosis of reactive lymphadenopathy in fine needle aspiration biopsy specimens

Reactive or benign lymphadenopathies were cytologically diagnosed in the aspirates of 62 (23.5%) of 265 cases with enlarged lymph nodes of the head, neck or inguinal region subjected to fine needle aspiration (FNA) biopsy. The cytomorphologic features characteristic of reactive lymphadenopathy are described in detail; some of the cell patterns were suggestive of a specific disease process. The similarities of cells and cell patterns that may pose differential diagnostic problems with malignant lymphomas are pointed out. This study emphasizes the role of FNA cytology in the diagnosis of some benign conditions.     

Posters. P19 Cervical carcinoma with metastases to the tympanic membrane: an unusual presentation

Introduction Fine needle aspiration (FNA) is a well‐established diagnostic technique which is frequently used to diagnose head and neck neoplasms. Clinical decisions concerning treatment of malignant salivary gland tumours, the extent of surgery and advisability of pre‐operative irradiation can be helped by prior knowledge of tumour type. Aim The aim of this study was to do an audit of all salivary gland FNAs carried out in Beaumont Hospital over a 14‐year period. Methods All salivary gland FNAs between 1989 and 2002 were reviewed. Where available, the corresponding follow‐up histological specimens were studied. Results During this 14‐year period, 305 patients with salivary gland lesions had FNA of the lesion performed. The total number of aspirates performed was 343. Of these, 184 had histologies available for follow‐up. Eighty‐nine aspirates were reported as inadequate; 89 as inflammatory, normal or consistent with cyst contents. One hundred and thirteen aspirates were diagnosed as a benign entity. Thirty‐three aspirates were reported as malignant (21 of which were felt to be primary to the salivary gland and 12 metastatic). Sixteen cases were called suspicious. Good correlation between FNA findings and histology was seen in the majority of cases (145 of 183). Some diagnostic problem areas were identified. These included the following: lymphomas (seven called benign on FNA), Warthin's tumour (seven not diagnosed or misdiagnosed on FNA) and mucoepidermoid carcinoma (one reported as pleomorhic adenoma and one as benign/cystic on FNA). Seven pleomorphic adenomas were not diagnosed on FNA pre‐operatively, predominantly due to inadequacy of the specimen. Three other malignancies (acinic cell carcinoma, lymphoepithelial carcinoma and carcinoma ex‐pleomorphic adenoma), while not diagnosed on FNA, were called suspicious, with re‐biopsy advised. Conclusion FNA cytology of salivary glands is an accurate method for evaluation of both benign and malignant lesions, enabling optimum surgical and adjuvant therapy decision‐making pre‐operatively. Well‐defined problem areas are identified and, therefore, clinicopathological correlation is required in these cases.     

Improving recognition of thyroid carcinoma in rapid-consultation specimens

OBJECTIVE: To improve recognition of thyroid carcinoma in rapid consultation on Diff-Quik-stained (Fisher Diagnostics, Middletown, Virginia, USA.) fine-needle aspiration (FNA) and rapid hematoxylin-eosin (H-E)-stained intraoperative scrape preparation (ISP) specimens by assessing 3 variables (anisokaryosis, nuclear overlap [NO] and scant/absent colloid) in cases of cellular follicular lesions (CFL), an indeterminate diagnostic category. STUDY DESIGN: Thirty-seven FNAs and 28 ISPs diagnosed as CFL, with histologic follow-up, were evaluated in blinded fashion by 3 cytopathologists assessing the 3 variables. RESULTS: Over 90% of the malignant cases showed NO in both FNA and ISP, while only 22% of the benign cases did; positive and negative predictive values (PPV and NPV) were 82% and 100%. All malignant cases showed significant anisokaryosis in both FNA and ISP in contrast to 24% of benign cases; PPV and NPV were 74% and 100%. Scant/absent colloid was seen in 87% and 39% of malignancies in FNA and ISP, respectively, as compared to 55% and 20% of the benign cases. PPV and NPV were 52% and 83% in FNA and 63% and 60% in ISP, respectively. CONCLUSION: Application of these variables improves recognition of thyroid carcinoma, particularly in fine needle aspirates, while additional material may be requested. With ISP, their absence supports recommending against further surgery. Together, optimal surgical planning and outcome may be obtained.     

Fine needle aspiration cytology of the malignant variant of ossifying fibromyxoid tumor of soft parts: a case report

BACKGROUND: Ossifying fibromyxoid tumor (OFMT) of soft parts is a rare, recently defined, fibroosseous neoplasm, generally regarded as clinically benign; however, one-third of cases recur locally, and several malignant examples have been reported. Fine needle aspiration (FNA) cytology of the tumor is rarely described in the literature. We provide the first cytomorphologic study of the malignant variant. CASE: A 70-year-old man presented with an intramuscular mass in the right buttock. Computed tomography revealed ossification within the mass and multiple pulmonary nodules. FNA biopsy showed round and polygonal to spindled tumor cells, arrayed singly, cordlike or in small aggregates, with scattered dense stromal fragments and a slightly myxoid background. The nuclei showed significant pleomorphism accompanied by coarse chromatin with clumping, irregular contours, and one to two distinct nucleoli. The tumor cells were recognizable as sarcoma, with no evidence of high grade malignancy. The tumor was totally excised, histopathologically confirmed as the malignant variant of OFMT of soft parts, and immunohistochemically and ultrastracturally analyzed as of neural origin. CONCLUSION: The FNA specimen revealed that the cytomorphology was consistent with the histologic features of the malignant variant of OFMT, but several characteristic histologic parameters, such as multilobular proliferation and peripherally placed mature, bony trabeculae, were not reflected in the aspirates. Although FNA cytologic findings may be of limited diagnostic utility in OFMT, radiographic evidence of calcification/ossification suggests that OFMT should be subjected to differential diagnosis with fine needle aspiration biopsy of soft tissue tumors. Additional studies will be required for further clarification.     

Kikuchi's histiocytic necrotizing lymphadenitis. Diagnosis by fine needle aspiration

Two cases of Kikuchi's histiocytic necrotizing lymphadenitis diagnosed by fine needle aspiration (FNA) of enlarged lymph nodes are reported. The FNA smears contained randomly activated lymphoid cells, necrotic debris, karyorrhectic cells and prominent histiocytes, suggesting the presence of reactive lymph nodes. The true nature of the lesions was evident from the examination of cell block sections prepared from tissue fragments in the aspirates, which preserved the architectural relationships of the different cell types. The same patterns were found in retrospectively and subsequently examined excised lymph nodes from these cases. The differential diagnosis of this entity, which may simulate a malignant lymphoma because of the presence of large numbers of activated lymphoid cells, is discussed and the value of preparing FNA cell blocks is emphasized. Though this rare benign disease may be suspected clinically in the more typical cases, such as young women with cervical lymphadenopathy, fever, neutropenia and otherwise excellent condition, the diagnosis cannot be made without a lymph node biopsy, which FNA may be able to provide in some instances.     

Galectin-3 is not useful in thyroid FNA

INTRODUCTION: Previous studies have suggested that galectin-3 immunohistochemistry may be useful in the fine needle aspiration (FNA) diagnosis of thyroid carcinoma as it has been reported to selectively stain carcinomas and not adenomas or goitres. METHODS: Fifty-one patients were included in a prospective study of galectin-3 in thyroid FNA; 88.2% were female and 11.8% male, mean age 53 years, range 25-87 years. Cell blocks were prepared and stained for galectin-3 if any cells were present in needle washings from the respective FNAs. RESULTS: Twelve of 51 (23.5%) of cell blocks contained epithelial cells. One benign and one inadequate FNA were negative for galectin-3 staining. One of five non-diagnostic FNA cases, a papillary carcinoma on final histology showed positive staining. Four follicular neoplasm/suspicious of carcinoma cases showed negative staining. One malignant FNA case, a papillary carcinoma showed positive staining with galectin-3 but three further carcinomas, two papillary and one follicular were galectin-3 negative. CONCLUSION: Galectin-3 immunohistochemistry does not appear to be a useful adjunct to diagnosis in thyroid FNA as it does not reliably distinguish malignant and benign lesions. Many thyroid aspirates are of low cellularity and are not suitable for cell block immunohistochemistry.     

Salivary gland tumors with a prominent oncocytic component. Cytologic findings and differential diagnosis of oncocytomas and Warthin's tumor on fine needle aspirates

OBJECTIVE: To review aspirates from histologically documented oncocytomas and Warthin's tumor (WT) to highlight the cytomorphologic findings and determine the difficulties encountered in typing oncocytepredominant aspirates. STUDY DESIGN: Over a 19-year period (1982-2000) we reviewed aspirates from 45 cases with an oncocyte preponderance. In 24 of them tissue for histologic examination was available (5 oncocytomas and 19 WT). RESULTS: In 4 of the 5 histologically documented oncocytomas the aspirates were cellular, with oncocytic epithelial cells in sheets, papillary fragments and singly. Epithelial atypia was minimal and lymphoid component absent, though scant proteinaceous material with a sprinkling of lymphocytes was seen. In WT moderate (35%) to abundant (28%) oncocytic epithelial cells were seen predominantly in a sheetlike arrangement with occasional papillary fragments and single cells. A variable quantity of lymphoid component was seen in 90% of the aspirates, with 88% of them showing a proteinaceous background accompanied by necrotic debris in 43% of cases. Squamous metaplasia was identified in 30% of cases, with 3 showing atypical squamous cells. In four cases the lymphoid component was scant and oncocytes abundant, and both possibilities were entertained. CONCLUSION: Fine needle aspiration cytology is fairly accurate in the preoperative diagnosis of WT. When the lymphoid component, mucus and necrotic background are minimal or absent, the tumors can be confused with oncocytoma. In oncocytoma, the oncocytic epithelial cells are more often seen in papillary fragments, acini and singly in comparison to WT, where sheets of oncocytic cells are observed. Some degree of epithelial atypia can be seen in oncocyte-predominant benign lesions. Squamous metaplasia, especially if accompanied by atypia and necrosis, can prove challenging.     

Peripheral endothelial cells are not reliable in differentiating primary benign and malignant hepatocellular lesions in fine needle aspirates of the liver

The distinction of hepatocellular carcinoma (HCC) from benign lesions of the liver in fine needle aspiration (FNA) specimens can be problematic. In an attempt to separate well-differentiated HCC from benign hepatocellular lesions, the presence of tissue fragments displaying peripheral endothelial cells (PE) has been proposed in a previous study as a useful feature in favour of malignancy. In this study, we evaluated slides from 59 cases of liver masses undergoing FNA (19 HCC, 40 benign) and evaluated them for the presence of tissue fragments containing PE. We found that 90% of cases of HCC contained tissue fragments in which PE were either focally present or abundant. However, 68% of cases containing only benign hepatocytes also contained tissue fragments in which PE were at least focally present. In addition, it appears that within the group of benign lesions, the presence of PE was related to the overall cellularity of the specimen rather than the specific nature of the lesion. Thus, the presence of PE in tissue fragments does not, in isolation, appear to be a useful morphological feature for the separation of benign and malignant hepatocellular lesions in FNA material.     

Cytologic features of clear cell carcinoma of the female genital tract. Diagnostic value of the "raspberry body" in nonexfoliative cytologic specimens

OBJECTIVE: To evaluate the presence of basement membrane stromal material in fine needle aspiration (FNA) and scrape cytologic specimens from patients with clear cell carcinoma (CCC) of the female genital tract. STUDY DESIGN: The study group consisted of 6 patients with CCC (5 ovarian and 1 cervical). Four samples corresponded to FNA specimens and 3 to scrape material obtained during intraoperative consultation for ovarian tumors. FNA was performed on a pelvic recurrence and on liver, pulmonary and lymph node metastases. The 6 cases had a complete histopathologic study. RESULTS: In addition to large, clear cells, all cases showed basement membrane stromal material that assumed several forms. The most common was globular, hyaline structures, either naked or surrounded by neoplastic epithelial cells ("raspberry bodies"). Other fragments were larger, with several spherules and elongated prolongations. Scrape material showed stromal material resembling reduplicated basement membrane material. In Diff-Quik-stained smears (QCA, Tarragana, Spain) it showed metachromatic staining with a pink to purple color. Its recognition on Papanicolaou-stained smears was more difficult since it did not stain or was gray. CONCLUSION: Basement membrane stromal material and, more precisely, "raspberry bodies," are a characteristic cytologic feature of CCC of the female genital tract. The combination of clear, atypical cells and basement membrane stroma is highly specific to this neoplasm and can be observed not only in exfoliative specimens but also in FNA and scrape samples.     

Serial fine needle cytology in the diagnosis of esophageal cancer

OBJECTIVE: To describe a method of registering local spread of cancer in the esophageal wall through serial endoscopic fine needle aspiration (FNA), to evaluate FNA as a diagnostic tool as compared to histologic biopsies and brush cytology, and to investigate cytologic appearances of aspirates and correlate them with survival STUDY DESIGN: Fifty-two patients with esophageal cancer were investigated with serial FNA every second centimeter from the upper esophageal sphincter aborally down to the level of macroscopic tumor. Histologic biopsies and brush cytologies were then performed. RESULTS: Of investigated cases, 33% showed malignant or suspect malignant cells from macroscopic tumor, at > or = 4 cm orally, as did 3 of 12 patients at 14 cm. FNA was more sensitive than brush cytology in establishing the diagnosis. A high ratio between the numbers of benign and malignant cells in aspirates from gross tumor tissue correlated with shorter survival (P < .03). CONCLUSION: Serial FNA can demonstrate local microscopic tumor spread in the wall of the esophagus in vivo in esophageal cancer patients. FNA is also a useful adjunct in establishing the diagnosis. Finally, evaluations of tumor cytology may have prognostic value.     

Fine needle aspiration cytology presentation of bilateral mammary fibromatosis. Report of a case

A case of bilateral fibromatosis of the breast occurring in a 22-year-old woman is described. The cytologic findings in fine needle aspirates included numerous stromal cells of the fibroblastic type, without atypia, in a background of granular amorphous material. Small fragments of collagen were present. Clusters of benign epithelial cells were occasionally observed.