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Prominent myofibroblastic differentiation. A pitfall in the diagnosis of dermatofibroma.

Myofibroblastic differentiation occurs in 10-20% of all dermatofibromas, affecting < 25% of cells. We report on a series of 36 dermatofibromas collected from > 1,500 fibrohistiocytic lesions (2%), with more prominent (> 25%) myofibroblastic differentiation characterized by markedly slender and elongated spindle cells positive for smooth muscle markers. While most of the lesions did not otherwise differ from ordinary dermatofibromas, three cases (0.2%) from the neck-shoulder region of male adults showed extensive myofibroblastic features (> 90%). Clinically, these three lesions measured approximately 1 cm and had a firm consistency, with the differential diagnosis of some fibrohistiocytic tissue response. Histologically, densely packed cells and prominent, partially nodular, stromal sclerosis with focal palisading of nuclei indicate some overlap with other rare variants of fibrohistiocytic tissue response, such as cellular benign and palisading cutaneous fibrous histiocytoma. Yet, these features together with focal whorled nesting of more epithelioid cells (one case) also caused considerable diagnostic problems to exclude other myofibroblastic as well as (malignant) spindle cell lesions such as (palisaded) myofibroblastoma, dermatofibrosarcoma protuberans, and neurothekeoma. Immunohistochemically, all lesions were markedly (> 90%) labeled for smooth muscle markers (HHF35, anti-SMA) and with NK1C3 (CD57), while a broad panel for other spindle cell tumors, such as pan-keratin, S100 protein, EMA, desmin, CD34, CD31, and KiM1p, were negative. Electron microscopy of two cases revealed prominent endoplasmic reticulum and Golgi complex, numerous intermediate filaments, attachment plaques, and focal basal lamina formation. No recurrence was seen during a follow-up of 9 (two cases) and two years, respectively.

Actin Cytoskeleton↗

Tumors with smooth muscle differentiation.

BACKGROUND: In the classification of tumors of soft tissue, modern schemes describe tumors by the normal adult tissue type the tumor resembles. Thus, tumors are described as smooth muscle tumors if the cells are differentiating towards smooth muscle. We may infer that in fact the tumor arose from smooth muscle, but this is only an inference. Tumors showing differentiation towards smooth muscle include hamartomas, benign tumors, and malignant tumors. OBJECTIVE: This review article describes the clinical presentation and course, histology, and treatment recommendations for benign and malignant smooth muscle tumors. METHODS: An extensive literature review of tumors with differentiation towards smooth muscle. RESULTS: Benign tumors exhibiting differentiation towards smooth muscle include smooth muscle hamartoma and leiomyoma. Myofibroma is a third tumor that some have argued is a smooth muscle tumor rather than a fibroblastic tumor. Characteristic fusiform shaped cells with a round central nucleus arranged in fasicles suggest smooth muscle differentiation. Special stains such as phosphotungenistic acid-hemotoxilin, analine blue, and Masson's trichrome are helpful in differentiating muscle from collagen. Immunohistochemical stains are also helpful in establishing a diagnosis. With solitary tumors, treatment for cosmesis or for painful leiomyomas is not a problem. Multiple leiomyomas, which may be painful or sensitive to cold or touch, are a therapeutic challenge, with reports of multiple medications being attempted in the literature. Leiomyosarcoma are malignant tumors of smooth muscle. They may be cutaneous and presumably arise from the arrector pilorum muscle, or subcutaneous, where they are believed to arise from vascular smooth muscle. Cutaneous leiomyosarcomas frequently reoccur following excision, but rarely metastasize. Subcutaneous leiomyosarcomas frequently reoccur following excision and have a high metastatic rate. Several recent reports have documented an increased frequency of visceral leiomyosarcomas in immunosuppressed patients. These tumors have been found to contain the Epstein Barr virus. Treatment of leiomyosarcoma is wide excision. CONCLUSIONS: Smooth muscle tumors are rare neoplasms that may confront the dermatologic surgeon. While leiomyomas are benign, their frequent sensitivity or pain necessitates treatment. Leiomyosarcomas are malignancies with a high reoccurrence rate, and when deep, a high metastatic rate. The finding of an increased frequency of visceral leiomyomas and leiomyosarcomas in immunosuppressed patients may imply an increased frequency of cutaneous leiomyomas and leiomyosarcomas in this patient population.

Hamartoma↗

[Congenital smooth muscle hamartoma. Clinical-histological considerations (3 cases)].

The Authors report 3 cases of "Congenital Smooth Muscle Hamartoma" (CSMH). CSMH presents as congenital patches or slightly indurated plaques with prominent overlying hair, often hyperpigmented. Histopathologic examination showed increased numbers of well-defined smooth muscle bundles in the superficial and deep dermis. CSMH and Becker's nevus should be considered in the differential diagnosis of any congenital hairy hamartoma.

Adolescent↗

Origin of granules in granular cell tumor. Intracellular myelin formation with autodigestion.

Eight cases of granular cell tumor were stained with Luxol fast blue to look for the presence of myelin. Luxol fast blue-positive granules were present in all cases. One case was studied ultrastructurally. It showed evidence of origin of granules as infoldings of cell membrane by a process similar to myelin formation around axons. These infoldings subsequently appear to be phagocytosed by lysosomes, resulting in the typical granules of the granular cell tumor.

Abdominal Muscles↗

New type of chimeric fusion product between the EWS and ATFI genes in clear cell sarcoma (malignant melanoma of soft parts).

We report a new case of clear cell sarcoma (CCS) harboring the t(12;22)(q13;q12). Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the presence of a chimeric transcript between the EWS and ATFI genes, both in primary and metastatic tissue. Sequencing studies disclosed an in-frame fusion between EWS gene codon 265 and ATFI gene codon 110. This breakpoint has not been reported previously and indicates an important in vivo loss of EWS and ATFI gene domains, which could be associated with the unusually aggressive behavior of this tumor.

Adult↗

Proliferation, ploidy and prognosis in uterine smooth muscle tumours.

DNA ploidy, mitotic rate (per 10 high power fields), mitotic index (per 1000 tumour nuclei), Ki-67 labelling index and S phase fraction were measured in 23 uterine leiomyosarcomas and 10 tumours of uncertain malignant potential. Correlations were calculated by Spearmann rank correlation. Univariate survival analysis was performed by log rank analysis and multivariate analysis performed by the Cox linear regression method. Ki-67 index and S phase fraction were significantly higher in leiomyosarcomas than in tumours of uncertain malignant potential. There was significant correlation between mitotic rate, mitotic index, Ki-67 index and S phase fraction in cases of leiomyosarcoma. Fifteen of 22 leiomyosarcomas and one of 10 tumours of uncertain malignant potential were DNA aneuploid. On univariate analysis of all the smooth muscle tumours, DNA ploidy, presence of significant nuclear atypia and presence of coagulative tumour cell necrosis were associated with outcome. Only DNA ploidy was associated with outcome in the group of leiomyosarcomas. On multivariate analysis of all of the smooth muscle tumours, DNA ploidy, age and grade of atypia were independently associated with outcome. No single factor was independently predictive of outcome in the group of leiomyosarcomas. Alternative indices of cell proliferation correlate with mitotic rate in uterine leiomyosarcoma and do not provide additional useful prognostic information. DNA ploidy, age and grade of atypia are independently associated with outcome in uterine smooth muscle tumours and measurement of DNA ploidy may be useful in identification of cases with an adverse prognosis.

Adult↗

[A case report of skeletal muscle metastasis of renal cell carcinoma effectively treated with interferon-alpha].

The skeletal muscle is a very rare site of metastasis in renal cell carcinoma. We report the third case of skeletal muscle metastasis of renal cell carcinoma effectively treated with interferon-alpha. The patient was a 74-year-old woman who had undergone radical nephrectomy on the left side for renal cell carcinoma on April 23, 1990, and had been observed as an outpatient. In June 1997, she was admitted with a diagnosis of metastasis in the left great adductor muscle and right sixth rib, as well as multiple lung metastasis. The metastatic lesion in the great adductor muscle decreased in size by more than 50% following concomitant intramuscular administration of natural interferon-alpha (nIFN-alpha). In the other metastatic lesions, nIFN-alpha-sensitive and resistant metastatic foci were intermingled. Thus, the primary focus in the present study was presumably composed of several clones with different sensitivities to nIFN-alpha.

Aged↗

Complex multilocular cystic lesion of rete testis, accompanied by smooth muscle hyperplasia, mimicking intratesticular Leydig cell neoplasm.

Non-neoplastic smooth muscle cell proliferation occurs under a variety of circumstances in many body organs. These abnormalities have been described as hypertrophy, hyperplasia or hamartomatous proliferations. In the male genital system, the excessive growth of smooth muscle in spermatic cord or paratesticular tissue is rare. In previously described cases, these lesions presented as masses but lacked the microscopic features of a neoplasm. We describe a complex multilocular cystic lesion composed of cystic transformation of the rete testis associated with smooth muscle proliferation mimicking intratesticular Leydig cell neoplasm. The lesion consists of three separate components: (1) cystic dilatation of the rete testis; (2) diffuse, interstitial smooth muscle proliferation with intraseptal expansion; and (3) extensive stroma with myxoid areas and scattered interstitial Leydig cells. These morphological findings, supported by a wide immunohistochemical panel, are consistent with cystic dilatation of the rete testis associated with smooth muscle hyperplasia, most probably of myoid origin. To the best of our knowledge, no similar complex lesion of the rete testis has yet been reported.

Adult↗

Fibromatosis colli of infancy: variability of sonographic appearance.

PURPOSE: We describe the variable sonographic appearances of fibromatosis colli, a disease that presents as a mass-like enlargement of the sternocleidomastoid muscle during the first 8 weeks of life. METHODS: Sonograms and records of 12 infants who presented with a sternocleidomastoid mass or torticollis before they were 12 weeks old were retrospectively reviewed for sonographic features (presence of a mass, diffuse muscle enlargement, and echogenicity), medical history, and follow-up data. RESULTS: Sonographically, 6 infants had only a mass in the sternocleidomastoid muscle, 2 had a mass with fusiform muscle enlargement, and 4 had only muscle enlargement. Five masses were hyperechoic, and 1 mass was of mixed echogenicity. The 2 masses associated with muscle enlargement were hypoechoic. Three cases of diffuse muscle enlargement were of mixed echogenicity, and 1 was hypoechoic. Unusual variations included (1) a mass split longitudinally into 2 components and (2) a diffusely enlarged muscle with a striated pattern of mixed echogenicity. Follow-up in 10 patients at 4 months and in 7 patients at 6 months showed clinical improvement. CONCLUSION: Fibromatosis colli usually appears sonographically as a hyperechoic mass or diffuse sternocleidomastoid enlargement of mixed echogenicity. Variations in its appearance should not prevent the correct diagnosis as long as the abnormality is intramuscular and adjacent soft tissues are normal.

Fibroma↗