Cytomorphologic Features of Low-Grade Endometrial Stromal Sarcoma

Transcription

1 Anatomic Pathology / LOW-GRADE ENDOMETRIAL STROMAL SARCOMA Cytomorphologic Features of Low-Grade Endometrial Stromal Sarcoma Maria Luisa Policarpio-Nicolas, MD, Helen P. Cathro, MD, Sarah E. Kerr, MD, and Edward B. Stelow, MD Key Words: Endometrial stromal sarcoma; Low grade; Cytology; Gynecologic; Nongynecologic; Fine-needle aspiration; Papanicolaou test Abstract Endometrial stromal sarcomas are uncommon tumors of the uterus, and the cytologic features have only been reported in a number of case reports that mostly discuss the features of higher grade undifferentiated sarcomas. This article discusses the cytologic features of a large series of low-grade endometrial stromal sarcomas (ESSs) sampled by a variety of methods. We reviewed our histologic files for all confirmed cases of low-grade ESS, and followed this by a computerized search for any corresponding cytologic specimens. We identified 12 Papanicolaou tests and 9 nongynecologic specimens. Most cases showed moderate to marked cellularity with a combination of single cells and stromal fragments. Blood vessels, interspersed between the clusters of stromal cells, were seen in 15 cases; 4 of these had supporting hyaline matrix. The cells were predominantly spindle shaped with scant to moderate cytoplasm, round to ovoid nuclei, and fine chromatin. Mitotic figures and nucleoli were rare. Most cases had a clean background. Endometrial stromal tumors are uncommon mesenchymal neoplasms of the uterus that histologically and immunophenotypically resemble the normal endometrial stroma. The most recent World Health Organization classification for tumors of the uterus classifies the tumors based primarily on tumor margin status and cytologic features. 1 Tumors that are circumscribed and have pushing margins are classified as stromal nodules, whereas those with infiltrative borders are classified as stromal sarcomas. Low-grade endometrial stromal sarcomas (ESSs) are clinically indolent malignancies with minimal cytologic atypia and proliferative activity. Undifferentiated sarcomas (previously categorized as high-grade endometrial stromal sarcomas) are highly aggressive malignancies that show substantial cytologic atypia and high mitotic activity. These tumors may be sampled cytologically before or after histologic confirmation and can be encountered by cytopathologists in gynecologic and nongynecologic preparations. As of yet, the cytologic features of these tumors have been reported in only a small number of case reports or small series, and most reports seem to deal with the features of high-grade undifferentiated sarcomas This article discusses the cytologic features of a large series of these cases seen at our institution with particular attention to the features that have been previously reported. 2-5,8,13,14 The differential diagnosis and the use of ancillary testing are also discussed. Materials and Methods A 15-year retrospective computerized search of the cytopathology files of the University of Virginia, Charlottesville, was reviewed for all histologically confirmed Am J Clin Pathol 2007;128:

2 Policarpio-Nicolas et al / LOW-GRADE ENDOMETRIAL STROMAL SARCOMA endometrial stromal neoplasms sampled by cytology. There were a total of 12 gynecologic and 9 nongynecologic specimens from 9 different women with histologically proven low-grade ESS. No undifferentiated carcinomas (high-grade ESSs) or endometrial stromal nodules were identified that had cytologic samples. The gynecologic preparations included 11 vaginal preparations (2 liquid-based preparations [ThinPrep, Cytyc, Boxborough, MA] and 9 conventional smears) and 1 cervical preparation (liquid-based preparation [ThinPrep]). The 9 nongynecologic specimens included 8 fine-needle aspiration (FNA) specimens (3 from soft tissue sites, 2 from retroperitoneal masses, and 3 from pelvic masses) and 1 diaphragmatic washing. The FNA smears were both air-dried and stained with rapid Romanowsky reagent and fixed in alcohol and stained by the Papanicolaou (Pap) method at the discretion of the pathologist who performed the rapid assessment. All FNA smears had been assessed for adequacy and given preliminary diagnoses. The following cytologic features were assessed for each case regardless of sampling method: cellularity (tumor) of smears (minimal: hard to identify, few groups or single cells; moderate: easy to identify, yet not the majority of the cellular component; and marked: easy to identify and the majority of the cellular component), cellular architecture (single cells vs stromal fragments), supporting stromal tissue (eg, blood vessels, hyaline stromal matrix), the presence of comet cells 6,10,11 (spindle-shaped cells with eccentric nuclei and cytoplasmic tapering away from the nucleus), cell shape (spindled vs epithelioid), the degree of anisonucleosis (mild, moderate, or marked), the degree of anisocytosis (mild, moderate, or marked), and characteristics of tumor cell cytoplasm (indistinct/scant, moderate, or abundant), nucleoli (present or absent, small or large), and chromatin pattern (fine or coarse). Screening was performed for mitotic figures (number of mitoses per 1,000 tumor cells), and background material was characterized (clean, inflammatory, necrotic, or bloody). Results Gynecologic Specimens The cytologic features are shown in Table 1. Of the 12 gynecologic specimens, only 1 (the single cervical Pap test performed before tumor resection) showed minimal cellularity. All other cases, which were vaginal Pap tests or smears of recurrent tumor, showed moderate (5/11) or marked (6/11) tumor cellularity. Most cases (10/12) showed a relatively equal mixture of single cells and stromal fragments Image 1, whereas 2 of 12 showed mostly stromal fragments. Occasional small blood vessels could be identified Table 1 Cytologic Features of Low-Grade Endometrial Stromal Sarcoma * Gynecologic Fine-Needle Preparations Aspiration Cytologic Feature (n = 12) Specimens (n = 8) Tumor cellularity Minimal 1 (8) 0 (0) Moderate 5 (42) 4 (50) Marked 6 (50) 4 (50) Stromal fragments and 12 (100) 8 (100) single cells Stromal vessels only 9 (75) 7 (88) Stromal hyaline matrix only 0 (0) 5 (63) Both features 0 (0) 4 (50) Comet cells 0 (0) 4 (50) Spindled cells 12 (100) 8 (100) Epithelioid cells 12 (100) 4 (50) Naked nuclei 6 (50) 5 (63) Anisonucleosis Minimal 12 (100) 4 (50) Moderate 0 (0) 4 (50) Anisocytosis Minimal 12 (100) 3 (37) Moderate 0 (0) 5 (63) Nucleoli 0 (0) 2 (25) Mitotic figures 0 (0) 2 (25) Background Clean 6 (50) 5 (63) Bloody 5 (42) 0 (0) Inflammatory 0 (0) 3 (37) Necrotic 1 (8) 0 (0) * Data are given as number (percentage). The only gynecologic case that showed minimal cellularity was the single cervical Papanicolaou test obtained before diagnosis. All other gynecologic cases were recurrences diagnosed by vaginal Papanicolaou tests. within the stromal fragments of 9 of 12 cases; however, the characteristic hyaline stromal matrix seen with these tumors was not seen with any cases. Comet cells were not seen with any gynecologic preparations. All cases showed a combination of spindled and epithelioid cells. Of the 12 cases, 6 had naked nuclei. Intact cells showed a scant to moderate amount of delicate, amphophilic cytoplasm. Anisonucleosis and anisocytosis were minimal in all cases. All cases had fine chromatin with indistinct nucleoli. The background was clean in 6 cases, bloody in 5, and necrotic in 1. Mitotic figures were not seen with any of the cases. Most of our gynecologic specimens were recurrences and were signed out as consistent with low-grade endometrial stromal sarcoma with notes stating that the samples were compared with the patients previous biopsy or resection specimens, which appeared similar. The single preoperative case was signed out as atypical cells with abundant necrosis and endometrial cells present (see note). We then noted that the changes were consistent with the patient s diagnosis of ESS made by FNA of an omental nodule. It would have been interesting to retrospectively review the preoperative Pap tests of these patients and see if neoplastic cells were present, and, if present, whether there were some criteria 266 Am J Clin Pathol 2007;128: Downloaded 266 from

3 Anatomic Pathology / ORIGINAL ARTICLE A C that would help in differentiating this lesion from other entities. However, because our hospital functions as a tertiary care institution, we actually have no preoperative Pap tests from the patients other than the one already noted. Nongynecologic Specimens The cytologic features for these specimens are also shown in Table 1. The single diaphragm washing showed minimal tumor cellularity, mostly stromal fragments, and a clean background. Of the 8 FNA specimens, 4 showed moderate cellularity and 4 showed marked cellularity. Of the 8, 2 showed a predominance of stromal fragments, whereas the other 6 showed relatively equal amounts of stromal fragments and single cells. Small intervening blood vessels were seen within the stromal fragments of 7 of 8 cases, a hyaline stromal matrix was seen with 5 cases, and both features were noted in 4 of the 8 FNA specimens Image 2. Comet cells were seen in 4 of 8 cases Image 3. All cases had spindled B Image 1 A, Spindled tumor cells attached to a delicate blood vessel (Papanicolaou, 200). B, Epithelioid and spindled tumor cells in clusters with superficial squamous cells in the background (Papanicolaou, 200). C, Epithelioid cells arranged singly and in clusters attached to delicate blood vessels in a bloody background (Papanicolaou, 200). cells Image 4, and 4 of 8 also had an epithelioid component Image 5. Naked nuclei were seen in 5 of 8 cases, and intact cells had a scant to moderate amount of delicate cytoplasm in all cases. Of 8 cases, 4 showed moderate anisonucleosis, whereas the remaining cases showed minimal anisonucleosis. Of the 8 cases, 5 showed moderate anisocytosis and 3 showed minimal anisocytosis. Most cases (6) had inconspicuous nucleoli, whereas 2 had small nucleoli. All cases had fine chromatin, although 2 showed focal clumping. The background was clean in 5 cases, and 3 had prominent background inflammation. Mitotic figures (10-20/1,000 tumor cells) were seen in 2 of 8 cases Image 6. Of the 8 FNA cases, 1 had a cell block and l had a core biopsy specimen. Immunohistochemical analysis performed on the core biopsy specimen showed immunoreactivity of the tumor cells with antibodies to CD10 and vimentin and absence of immunoreactivity of the tumor cells with antibodies to keratin, S-100, inhibin, calretinin, CD117, and Am J Clin Pathol 2007;128:

4 Policarpio-Nicolas et al / LOW-GRADE ENDOMETRIAL STROMAL SARCOMA Image 2 Spindled tumor cells with interspersed blood vessels and eosinophilic, hyaline stromal matrix (Papanicolaou, 200). Image 3 Randomly dispersed spindled comet cells (Papanicolaou, 200). Image 4 Spindled tumor cells with scant hyaline matrix (rapid Romanowsky, 200). Image 5 Epithelioid and spindled comet cells with interspersed blood vessels (Papanicolaou, 200). smooth muscle actin, findings that supported the diagnosis of low-grade ESS. No ancillary studies were performed on the cell block because the morphologic features appeared similar to those of the prior total abdominal hysterectomy specimen. Of the 8 FNA smears, 7 were from recurrences and were signed out as consistent with low-grade endometrial stromal sarcoma with notes stating that the cytologic findings were similar to those seen in the patients prior materials. One case was an omental lesion with a concomitant core biopsy specimen on which immunohistochemical studies were performed, as described earlier in this paragraph. It was signed out as malignant sarcoma, favor endometrial stromal sarcoma. A note stated that given the clinical history of a large uterine mass and the immunohistochemical results, the findings were consistent with an ESS. 268 Am J Clin Pathol 2007;128: Downloaded 268 from Discussion Low-grade ESSs are rare malignant tumors that comprise only about 0.2% of all female genital tract malignancies.1 Women with these tumors have abnormal uterine bleeding, uterine enlargement, or pelvic pain. Compared with other uterine malignancies, they occur at an earlier age (42-58 years), and about 10% to 25% of the patients are premenopausal. The tumors have an indolent growth with a

5 Anatomic Pathology / ORIGINAL ARTICLE tendency for late recurrence. 15 Metastases are rarely detected before the diagnosis of the primary lesion. 1 Grossly, low-grade ESSs involve the endometrium, occasionally extensively. By definition, the tumors are infiltrative. Rarely, the tumors manifest as polyps, usually with hemorrhage or infarction. On the cut surface, the tumors are tan to yellow and appear as cords and nodules infiltrating through the uterine smooth muscle. The histologic features recapitulate the gross appearance with cords of tumor cells infiltrating between smooth muscle and within lymphatic spaces. The neoplastic stromal cells resemble those of the proliferative endometrium, are monotonous in appearance, and have relatively uniform size and shape. 1 Tumor cell nuclei are round to ovoid and have fine chromatin, and small, inconspicuous nucleoli may be seen. A small amount of cytoplasm is present, and cell borders are indistinct. Mitotic activity is usually low (<10/10 high-power fields). It should be noted that rare cases of low-grade ESS will have a greater number of mitotic figures, although this is not associated with an adverse prognosis. 16 Proliferating small vessels resembling the endometrial spiral arterioles are characteristic, and tumors can have bands of hyaline connective tissue separating islands and clusters of bland neoplastic stromal cells. 17 Cleft-like or rounded hyalinized vessels have also been noted with these tumors. Some tumors may be cellular and lack prominent vasculature, and some may exhibit a mixture of histologic patterns. Focal smooth muscle differentiation has also been observed. 18 A good number of articles have been recently published regarding the immunophenotype of low-grade ESS Tumor cells are usually immunoreactive with antibodies to CD10 and vimentin and are not immunoreactive with antibodies to keratins, epithelial membrane antigen, and caldesmon. Weak and focal immunoreactivity with antibodies for smooth muscle actin and desmin has been reported. 19 The previously described cytologic findings of lowgrade ESS such as bland cells occurring singly and small clusters, scant cytoplasm, small round or oval nuclei, fine chromatin pattern, and occasional small prominent nucleoli 2-5,8,13,14 were observed in our series. In 88% of our cases, small intervening blood vessels were observed, a finding that was noted previously in a single article. 2 Interestingly, comet cells, which were reported only in cervical-vaginal smears of patients with high-grade ESS, 6,8,10,13 were observed not in cervical or vaginal smears in the present study, but instead, in 4 of our FNA cases. Metachromatic hyaline stromal matrix, described in FNA smears of lowgrade ESS 2 and high-grade ESS 12 were observed only in 5 cases. Morimoto et al 13 studied the value of mitotic activity in differentiating low-grade (1.9/1,000 tumor cells) from high-grade (14.1/1,000 tumor cells) stromal sarcoma. Image 6 Tumor cells with mitotic figures (Papanicolaou, 400). Although most of our cases did not show mitosis, 2 cases had brisk mitotic activity. Undifferentiated sarcoma can show many of the same features, and these tumors are distinguished from low-grade ESS by the presence of hemorrhage or necrosis, the degree of cytologic atypia, and the number of mitotic figures Furthermore, the vascular pattern that is typical of low-grade ESS is usually lacking with undifferentiated sarcoma. These features can be assessed by cytologic examination, and, likely, one could at least favor one diagnosis over the other with cytologic examination only. On Pap test, the differential diagnosis for low-grade ESS Table 2 would have to include a number of benign conditions, including normally shed endometrial cells, endometriosis, and even submucosal leiomyoma. With our recurrent gynecologic cases, tumor cellularity was far greater than what one usually sees in these nonneoplastic or benign conditions. The single case we identified with a preoperative Pap test, however, showed a much more limited cellularity, and we were likely only able to make the diagnosis because of a concomitant pelvic FNA specimen. We believe the preoperative diagnosis of these lesions by Pap test would, thus, be very difficult because tumor cellularity may be low and the cytologic features are relatively bland and would not be easy to differentiate from nonneoplastic stroma. Our belief is quite similar to the results of 2 studies in which low-grade ESS was not detected in preoperative cervical and vaginal smears from the patients. 8,13 By FNA, the cytologic features better recapitulate the histologic features, and a vascular and hyalinized stroma are often seen. 2 Nevertheless, we are not sure how predictive any of these features would be for the diagnosis of Am J Clin Pathol 2007;128:

6 Policarpio-Nicolas et al / LOW-GRADE ENDOMETRIAL STROMAL SARCOMA Table 2 Differential Diagnoses for Low-Grade Endometrial Stromal Sarcoma Gynecologic specimens (Papanicolaou test) Common Normal endometrium or lower uterine segment Endometriosis Smooth muscle tumor Less common Sarcomatoid carcinoma (cervical or endometrial) Perivascular epithelioid cell tumor Nongynecologic specimens, pelvic mass (fine-needle aspiration specimens) Common Endometriosis Smooth muscle tumor Ovarian stromal tumor (eg, fibroma/thecoma) Less common Peripheral nerve sheath tumor Gastrointestinal stromal tumor Fibroblastic/myofibroblastic proliferation (eg, fibromatosis, solitary fibrous tumor, inflammatory myofibroblastic tumor) Monophasic synovial sarcoma Sarcomatoid carcinoma Sarcomatoid mesothelioma Perivascular epithelioid cell tumor low-grade ESS, and with a previously undiagnosed disease, one s differential diagnosis would have to include a slew of monomorphous spindle-cell neoplasms (Table 2), which include, among others, endometriosis, ovarian stromal tumors, solitary fibrous tumor 26 /myofibroblastic lesions, smooth muscle tumors, 27 peripheral nerve sheath tumors, 28,29 and monophasic synovial sarcoma. 30 It is doubtful that one would be able to definitely distinguish these lesions without the assistance of immunohistochemical analysis, and it is important for one to include low-grade ESS in the differential diagnosis for spindle-cell neoplasia of the pelvis or juxtaposed soft tissue of the woman. Most cytologic samples of low-grade ESS will include a combination of single cells and stromal fragments with interspersed blood vessels. Individual cells will have fine chromatin and a scant to moderate amount of cytoplasm with minimal anisonucleosis and anisocytosis. Metachromatic hyaline stromal matrix and intervening vessels, if present together, may assist with the diagnosis on an FNA specimen but cannot usually be identified with gynecologic preparations. Because of the bland morphologic features of these tumors, familiarity with their clinical and cytologic features may allow one to correctly diagnose or, at least, suggest the diagnosis of these lesions. From the Department of Pathology, University of Virginia, Charlottesville. Address reprint requests to Dr Stelow: Dept of Pathology, University of Virginia Health System, 3rd Floor, Hospital Expansion, Room 3001, 1215 Lee St, Charlottesville, VA References 1. Hendrickson MR, Tavassoli FA, Kempson RL, et al. Mesenchymal tumours and related lesions. In: Tavassoli FA, Devilee P, eds. Pathology and Genetics of Tumours of Breast and Female Genital Organs. Lyon, France: IARC Press; 2004: World Health Organization Classification of Tumours. 2. Yang GC. Fine needle aspiration cytology of low grade endometrial stromal sarcomas. Acta Cytol. 1995;39: Satoh Y, Ishikawa Y, Furuta N, et al. Difficulty of cytodiagnostic approaches to pulmonary metastases from a case of low grade endometrial stromal sarcoma [letter]. Acta Cytol. 2003;47: Reich O, Pickel H, Regauer S. Cytologic diagnosis of low grade endometrial stromal sarcoma by staining for estrogen and progesterone receptors. Acta Cytol. 2002;46: Yokosuka K, Abe S. Recurrent low grade endometrial stromal sarcoma in ascitic fluid. Acta Cytol. 2002;46: Hsiu JG, Stawicki ME. The cytologic findings in two cases of stromal sarcoma of the uterus. Acta Cytol. 1979;23: Wang X, Khoo US, Xue WC, et al. Cervical and peritoneal fluid cytology of uterine sarcomas. Acta Cytol. 2002;46: Ito E, Saito T, Suzuki T, et al. Cytology of vaginal and uterine sarcomas. Acta Cytol. 2004;48: Hong IS. The exfoliative cytology of endometrial stromal sarcoma in peritoneal fluid. Acta Cytol. 1981;25: Becker SN, Wong JY. Detection of endometrial stromal sarcoma in cervicovaginal smears: reports of three cases. Acta Cytol. 1981;25: Massoni EA, Hajdu SI. Cytology of primary and metastatic uterine sarcomas. Acta Cytol. 1984;28: Liu K, Krigman HR, Coogan AC. Hyaline matrix material in high-grade endometrial stromal sarcoma diagnosed by fineneedle aspiration: case report. Diagn Cytopathol. 1997;16: Morimoto N, Ozawa M, Kato Y, et al. Diagnostic value of mitotic activity in endometrial stromal sarcoma: report of two cases. Acta Cytol. 1982;26: Zaharopoulos P, Wong JY, Lamke CR. Endometrial stromal sarcoma: cytology of pulmonary metastasis including ultrastructural study. Acta Cytol. 1982;26: Shafi M, Luesley DM, Jorda JA. Gynecological Oncology. London, England: Churchill Livingstone; 2001: Evans HL, Chawla SP, Simpson C, et al. Smooth muscle neoplasms of the uterus other than ordinary leiomyoma: a study of 46 cases, with emphasis on diagnostic criteria and prognostic factors. Cancer. 1988;62: Al-Nafussi AI. Tumor Diagnosis: Practical Approach and Pattern Analysis. 2nd ed. London, England: Oxford University Press; 2005: Yilmaz A, Rush DS, Soslow RA. Endometrial stromal sarcomas with unusual histologic features: a report of 24 primary and metastatic tumors emphasizing fibroblastic and smooth muscle differentiation. Am J Surg Pathol. 2002;26: Zhu XQ, Shi YF, Cheng XD, et al. Immunohistochemical markers in differential diagnosis of endometrial stromal sarcoma and cellular leiomyoma. Gynecol Oncol. 2004;92: Toki T, Shimizu M, Takagi Y, et al. CD10 is a marker for normal and neoplastic endometrial stromal cells. Int J Gynecol Pathol. 2002;21: Am J Clin Pathol 2007;128: Downloaded 270 from

7 Anatomic Pathology / ORIGINAL ARTICLE 21. McCluggage WG, Sumathi VP, Maxwell P. CD10 is a sensitive and diagnostically useful immunohistochemical marker of normal endometrial stroma and of endometrial stromal neoplasms. Histopathology. 2001;39: Chu PG, Arber DA, Weiss LM, et al. Utility of CD10 in distinguishing between endometrial stromal sarcoma and uterine smooth muscle tumors: an immunohistochemical comparison of 34 cases. Mod Pathol. 2001;14: Gupta N, Rajwanshi A, Nijhawan R, et al. Metastatic granulosa cell tumor: diagnosed by fine-needle aspiration cytology [letter]. Diagn Cytopathol. 2006;34: Handa U, Ahal S, Mohan H, et al. Metastatic granulosa cell tumor: diagnosis by fine needle aspiration. Acta Cytol. 2004;48: Lal A, Bourtsos EP, Nayar R, et al. Cytologic features of granulosa cell tumors in fluids and fine needle aspiration specimens. Acta Cytol. 2004;48: Clayton AC, Salomao DR, Keeney GL, et al. Solitary fibrous tumor: a study of cytologic features of six cases diagnosed by fine-needle aspiration. Diagn Cytopathol. 2001;25: Barbazza R, Chiarelli S, Quintarelli GF, et al. Role of fineneedle aspiration cytology in the preoperative evaluation of smooth muscle tumors. Diagn Cytopathol. 1997;16: Resnick JM, Fanning CV, Caraway NP, et al. Percutaneous needle biopsy diagnosis of benign neurogenic neoplasms. Diagn Cytopathol. 1997;16: Domanski HA, Akerman M, Engellau J, et al. Fine-needle aspiration of neurilemoma (schwannoma): a clinicocytopathologic study of 116 patients. Diagn Cytopathol. 2006;34: Ewing CA, Zakowski MF, Lin O. Monophasic synovial sarcoma: a cytologic spectrum. Diagn Cytopathol. 2004;30: Am J Clin Pathol 2007;128: