Crystal-Deficient Alveolar Soft-Part Sarcoma With Cutaneous Involvement: A Case Report

ALK Gene Fusions in Epithelioid Fibrous Histiocytoma: A Study of 14 Cases, With New Histopathological Findings

Previous studies showed that ALK is often positive in epithelioid fibrous histiocytoma (EFH). Two cases of EFH with ALK gene fusions have been recorded. Our objective was to study a series of EFH to present histopathological variations of EFH, identify novel ALK gene fusions, and determine whether there is a correlation between histopathological features and particular gene. We investigated 14 cases of EFH, all ALK immunopositive. The cases were assessed histopathologically as well as for ALK and TFE-3 rearrangements using FISH and ALK gene fusions using next-generation sequencing. The analysis of the sequencing results was performed using the Archer Analysis software (v5; ArcherDX Inc). The study group consisted of 8 female and 6 male patients, ranging in age from 18 to 79 years (mean 42 years; median 37.5 years). All presented with a solitary lesion. Microscopically, most lesions were polypoid and composed of epithelioid cells with ample cytoplasm. In addition, a variable number of bi-, tri-, or multinucleated, spindled, multilobated, cells with eccentric nuclei, cells with nuclear pseudoinclusions, mucinous, and grooved cells were admixed. In 5 cases, the predominant epithelioid cell component consisted of rather small cells, whereas spindled cells dominated in 3 cases. Of these, 2 lesions were composed rather of pale eosinophilic to clear cells, occasioning a resemblance to PEComa or leiomyoma. Immunohistochemically, all cases expressed ALK and 11 were positive for TFE-3. The break apart test for ALK was positive in 11 cases, whereas specimens from the remaining 3 cases were not analyzable. ALK genes fusions were found in all but 3 cases and included SQSTM1-ALK (3), VCL-ALK (3), TMP3-ALK (2), PRKAR2A-ALK (1), MLPH-ALK (1), and EML4-ALK (1). No correlation between histological features and type of ALK fusion was found. TFE-3 break apart test was negative. It is concluded that ALK-immunopositive EFH shows ALK gene fusions that involve various protein-coding genes, implicated in a variety of biological processes. Rare variants of EFH rather consist of spindled "non-epithelioid" cells.

Alveolar Soft-Part Sarcoma of the Tongue

Alveolar soft-part sarcoma is a rare neoplasm of unknown histogenesis that accounts for less than 1% of all soft-tissue sarcomas. The tumor is highly vascularized with small vascular spaces separating nests of cells, and from cytogenetic point of view, is characterized by chromosome rearrangement der(17)t(X:17)(p11:q25) that results in the ASPL-TFE3 translocation. It can occur at any age, but it is most common between 15 and 35 years of age. The prognosis is poor, despite the relatively slow growth of the tumor. We present here an atypical case of alveolar soft-part sarcoma in which the age of the patient, the location, and the histopathologic characteristics of the lesion represented a diagnostic challenge.

CT, MRI, and FDG PET/CT in a patient with alveolar soft part sarcoma

Alveolar soft part sarcoma (ASPS) is a rare malignant soft tissue tumor. We present a case, who had a history of a left pulmonary ASPS resection 5 years ago, with a tumor in the left lower extremity showing high vascularity mimicking hemangioma on enhanced CT and MRI. This tumor showed intense FDG uptake on FDG PET/CT with SUVmax of 6.8, indicating a malignant soft tissue tumor. Complete resection of the tumor was performed. A diagnosis of ASPS was confirmed by pathology. This case highlights FDG PET/CT is helpful for differentiating ASPS from hemangioma according the degree of FDG uptake.

A distinctive translocation carcinoma of the kidney; "rosette forming," t(6;11), HMB45-positive renal tumor: a histomorphologic, immunohistochemical, ultrastructural, and molecular genetic study of 4 cases

To date, only a few cases of "rosette forming t(6;11), HMB45-positive renal carcinoma" have been published. In this article, we contribute further data on 4 cases of this rare entity. Patients were 3 women and 1 man with an age range of 20 to 54 years (median, 23 years). Follow-up (range, 3-5 years; median, 4 years) did not reveal any metastatic events or recurrences. All tumors were well circumscribed and mostly encapsulated with homogeneous gray to tan cut surfaces. No necrosis was seen. All tumors displayed a solid or solid/alveolar architecture and contained occasionally long and branching tubular structures composed of discohesive neoplastic cells and pseudorosettes. The presence of pseudorosettes was a constant finding, but the number of pseudorosettes varied significantly among cases. All cases displayed focal immunoreactivity for the melanocytic marker HMB45, cathepsin K, and vimentin. Melan A, tyrosinase, cytokeratins, CD10, and microphthalmia transcription factor were each positive in 3 of 4 cases. On ultrastructural examination, numerous electron-dense secretory cytoplasmic granules with some resemblance to melanosomes were identified. The pseudorosettes were composed of reduplicated basement membrane material surrounded by small lymphocyte-like neoplastic cells. Using reverse transcription polymerase chain reaction, 2 tumors were positive for the Alpha-TFEB fusion transcript. The presence of the translocation t(6;11)(Alpha-TFEB) was confirmed in 2 analyzed cases. No von Hippel-Lindau tumor suppressor gene mutation, promotor methylation or loss of heterozygosity of 3p was found. Losses of part of chromosome 1 and chromosome 22 were found in one case.