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The aim of this study was to describe 2 cases of primary peritoneal malignant mixed müllerian tumor (MMMT). Two patients with primary peritoneal MMMT were examined for their clinical and pathologic features. We describe 2 cases of primary peritoneal MMMT in which the carcinomatous and mesenchymal components were readily identifiable, predominantly involving the peritoneum, with no ovarian involvement. The peritoneum and ovaries, with their common embryologic origin, likely account for the peritoneum’s ability to undergo a similar malignant transformation, with the resultant genesis of an MMMT of peritoneal origin.

Chondroblastomas are rare bone tumors, accounting for less than 2% of all bone tumors. Although generally benign, there are instances of aggressive tumor behavior with extensive soft tissue invasion and even metastasis. In this report, we detail an instance where the tumor displayed extensive soft tissue invasion. As there is tumor heterogeneity in terms of morphologic appearance as well as a varied immunohistochemistry profile, a diagnosis of chondroblastoma may not be straightforward if the initial biopsy sample did not include the more characteristic area. In our case, the tumor expressed cytokeratin, calponin, and p63 in addition to S-100, potentially raising a diagnosis of a mixed tumor. The differential diagnosis and biologic behavior of chondroblastomas are discussed.

Carcinomas of müllerian origin involving colorectum in women with no concurrent or history of gynecologic malignancies are diagnostically challenging, and its histogenetic origin is uncertain. We reviewed 13 cases of carcinoma of müllerian origin with clinical presentation mimicking primary colorectal carcinoma. The patients' average age was 63.9 years. All except 2 patients presented with mass lesions in rectosigmoid colon or rectovaginal septum. The major presenting symptoms were rectal bleeding (4/13), rectosigmoid mass (6/13), vaginal mass (1/13), and abdominal pain or constipation (2/13). The average size of tumor was 4.2 cm (range, 2.4-15.0 cm). Among the 10 patients who underwent preoperative biopsy, 5 were diagnosed to have moderately and poorly differentiated colorectal carcinoma. All tumors were surgically resected with final diagnoses of moderately differentiated endometrioid carcinoma in 6 cases, mixed serous and endometrioid carcinoma in 4 cases, malignant mixed müllerian tumor in 2 cases, and undifferentiated carcinoma in 1 case. In 9 of 13 cases, foci of endometriosis were identified adjacent to or within the tumor. One case had endosalpingiosis. Immunohistochemical stains showed, after positive results, the following: cytokeratin 7 (CK7; 13/13), estrogen receptor (13/13), progesterone receptor (10/13), cytokeratin 20 (CK20; 0/13), and CDX-2 (0/13). In conclusion, carcinoma of müllerian origin often presents as bulky mass in rectosigmoid or rectovaginal septum clinically mimicking primary colorectal cancer. Endometriosis might be an important etiologic factor. Familiarities of this unusual clinicopathologic entity, careful morphologic evaluation, and immunohistochemical stain with a panel of markers (CK7, CK20, estrogen receptor, progesterone receptor, CDX-2) will be helpful for the correct diagnosis.

Sialoblastoma is a rare congenital or perinatal salivary tumor that varies in histologic features and biologic potential. Seven cases from the files of the Armed Forces Institute of Pathology are presented. These tumors occurred in 4 males and 3 females with ages ranging from prenatal to 6 months at the time of discovery. Five lesions originated from the parotid gland; 2 lesions were from the submandibular gland. All lesions presented as nodular to multinodular swellings and ranged in size from 2.0 to 7.0 cm. The principal sign or symptom was rapid growth. Two histologic patterns with differing behavior predominated: (1) a favorable pattern had semiencapsulation of cytologically benign basaloid tumor cells with intervening stroma; and (2) an unfavorable histology of anaplastic basaloid tumor cells, minimal stroma, and broad pushing to infiltrative periphery. Four and three tumors had favorable and unfavorable growth patterns, respectively. One unfavorable lesion had vascular invasion, and another demonstrated perineural invasion. All 3 tumors with unfavorable histology recurred. Tumor cells in 3 cases were immunohistochemically reactive for keratin, S-100, smooth muscle actin, and calponin to varying degrees. All 3 tumors were reactive for p63. alpha-Fetoprotein was expressed in 2 unfavorable tumors. Ki67 was expressed at 3% in a favorable tumor and 40% and 80% in the 2 unfavorable lesions. Treatment involved surgical excision. One patient received adjuvant chemotherapy. Two sialoblastomas resulted in recurrences within a year and another developed a recurrence after 4 years. One sialoblastoma developed lung metastasis within 1 month of the original biopsy. Although a clinical correlation is suggested by a favorable/unfavorable histologic grading system the biologic behavior is nonetheless considered unpredictable.

Corticomedullary mixed tumors of the adrenal gland are quite rare, with only five well-documented cases reported in the literature.(1-4) Herein, we report the light microscopic and immunohistochemical features of two cases of this rare tumor. Patient 1 is a 34-year-old woman who presented with hypertension, hair loss, and amenorrhea of 1-year duration. Patient 2 is a 52-year-old woman who presented with flank pain and what appeared to be a renal mass on arteriogram with no history of hypertension, Cushing's syndrome, or other endocrine abnormalities. At surgery, the tumor was noted to arise from the adrenal gland rather than the kidney and adrenalectomy was performed. In both cases, the surgically resected specimens consisted of a well-circumscribed, single adrenal mass surrounded by a rim of uninvolved adrenal cortical tissue. The tumors were composed of adrenal cortical cells intimately admixed with pheochromocytes. Immunohistochemical studies highlighted these two cellular components. The pheochromocytes were strongly reactive with chromogranin and the sustentacular cells with S-100 protein, whereas the adrenal cortical cells reacted specifically with inhibin. Thus, we report two additional cases of mixed corticomedullary tumor of the adrenal gland. Ann Diagn Pathol 5:304-308, 2001. This is a US government work. There are no restrictions on its use.

Eccrine spiradenoma (ES) is a benign tumor of the skin adnexal origin. It is often seen in the head and neck region of young adults and may be present for years. While there have been numerous case reports of malignant degeneration within ES, they have been mostly carcinomatous dedifferentiation and rarely carcinosarcomas. A malignant mixed tumor is a neoplasm with a malignant epithelial component and areas of chondroid and myxoid differentiation within the malignant epithelial proliferation. While the epithelial component is malignant, the mesenchymal component is felt to represent a benign, metaplastic response of the stroma. While the malignant mixed tumor has a benign counterpart, the benign mixed tumor, the former is usually not seen in continuity with the latter. We describe a case of ES with malignant degeneration and demonstrate the transformation from benign to malignant. The histology and immunohistochemistry of the neoplasm supports a malignant mixed tumor, an extremely unusual neoplasm to see in association with ES or any benign adnexal neoplasm.

Primary sebaceous carcinoma of salivary glands is a rare entity with approximately 22 de novo documented cases. Similar tumor arising in a benign mixed tumor has only been reported once. We report a second case of sebaceous carcinoma in a pleomorphic adenoma and discuss the clinicopathologic features, histogenesis, and the differential diagnosis of this unusual tumor.

Myoepithelial tumors of the soft tissues have only recently been described. Two cases of lower extremity malignant myoepithelial tumors are reported. One case of malignant mixed tumor overlying the gastrocnemius muscle was treated with wide local excision, but metastasized to regional lymph nodes 14 months after surgical excision. One patient with malignant myoepithelioma of the right lower leg was treated with limb amputation and is alive without disease at 46 months. A review of the literature discloses 120 additional cases of soft tissue myoepithelial tumors, 102 of which are myoepitheliomas and 18 are mixed tumors. Thirty-seven percent of the myoepitheliomas met the criteria for malignancy, and 33% of the mixed tumors were malignant. Of these, 30% had locally recurrent disease and 32% developed metastatic disease. Treatment benefit from chemotherapy and radiation therapy is unclear.

Malignant mixed tumor of salivary glands is a rare tumor whose variable behavior and prognosis are related for the most part to the clinical stage and histologic grade of the carcinomatous component. The purpose of this study is to predict prognosis by comparing the histologic grading and subclassification of the carcinomatous component with the immunohistochemical reactivity for E-cadherin, P53 mutation protein, and cellular proliferation (Ki67). Stains were performed on formalin-fixed paraffin-embedded tissue sections from 18 cases of malignant mixed tumor. Clinical follow-up was obtained for each patient. Regional lymph node and distant organ metastases were the criteria for poor prognosis. Of seven cases with lymph nodes metastasis, five were high-grade tumors (with one subsequent death from brain metastasis) and two were low-grade. Of the eight high-grade tumors, positivity for Ki67, p53, and E-cadherin were noted in six, four, and two cases, respectively. In contrast, of the 10 low-grade tumors, two stained with Ki67, five with p53, and none with E-cadherin. Most notably, all seven metastatic cases (as opposed to only one of 11 nonmetastatic tumors) had Ki67 reactivity of more than 10%. We conclude that malignant mixed tumor represents a spectrum of malignancies in which the clinical behavior is closely related to the carcinomatous element. In addition to histologic grading, Ki67 is a useful prognostic marker in the evaluation of malignant mixed tumor while p53 and E-cadherin appear to be of limited value.