ABSTRACT
BACKGROUND: Epithelioid fibrous histiocytoma (EFH) is an uncommon dermal neoplasm expressing anaplastic lymphoma kinase (ALK) protein. Rarely a histopathological variant of this entity exhibits exclusively spindle cells. We report three cases of EFH that do not completely fulfill phenotypic criteria featuring spindle cell morphology and expressing ALK protein. We also analyze the fusion partner genes rearranged with ALK in these cases. METHODS: ALK expression and rearrangement status were evaluated by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next generation sequencing based gene fusion analysis. RESULTS: Three cases, all from females between 25 and 55 years old, have been biopsied from back, left arm, and thumb. All three cases showed tumor with exclusively spindle cell morphology without any epithelioid cells. The tumor cells exhibited strong ALK expression by IHC and FISH study confirmed ALK gene rearrangement in all three cases. DCTN1-ALK fusion was identified in two cases. CONCLUSION: EFH is not always purely epithelioid and its spindled cell variant, spindle cell histiocytoma, should be included in the differential diagnosis of superficial dermal spindled cell neoplasms. ALK immunostain is a useful diagnostic marker for this entity and further studies may be useful to investigate whether DCTN1-ALK fusion mutations are specific to EFH with spindled cell features.
Subject(s)
Anaplastic Lymphoma Kinase/genetics , Epithelioid Cells/pathology , Histiocytoma, Benign Fibrous/genetics , Histiocytoma/genetics , Adult , Biomarkers, Tumor/metabolism , Biopsy , Diagnosis, Differential , Dynactin Complex/genetics , Female , Gene Fusion/genetics , High-Throughput Nucleotide Sequencing/methods , Histiocytoma/diagnosis , Histiocytoma/ultrastructure , Histiocytoma, Benign Fibrous/diagnosis , Histiocytoma, Benign Fibrous/ultrastructure , Humans , Immunohistochemistry/methods , In Situ Hybridization, Fluorescence/methods , Middle Aged , Neoplasms, Fibrous Tissue/pathologyABSTRACT
PURPOSE OF REVIEW: Since the discovery of B-Raf proto-oncogene (BRAF) V600E mutations in histiocytic neoplasms, diverse kinase alterations have been uncovered in BRAF V600E-wildtype histiocytoses. The purpose of this review is to outline recent molecular advances in histiocytic neoplasms and discuss their impact on the pathogenesis and treatment of these disorders. RECENT FINDINGS: Activating kinase alterations discovered in BRAF V600E-wildtype Langerhans (LCH) and non-Langerhans cell histiocytoses (non-LCH) result in constitutive activation of the mitogen-activated protein kinase and/or phosphoinositide 3-kinases-Akt murine thymoma pathways. These kinase alterations include activating mutations in A-Raf proto-oncogene, mitogen-activated protein kinase kinase 1, neuroblastoma rat sarcoma viral oncogene homolog, Kirsten rat sarcoma viral oncogene homolog, and phosphatidylinositol-4,5-bisphosphate 3 kinase, catalytic subunit α kinases in LCH and non-LCH; BRAF, anaplastic lymphoma receptor tyrosine kinase, and neurotrophic tyrosine kinase, receptor type 1 fusions, as well as the Ets variant 3-nuclear receptor coactivator 2 fusion in non-LCH; and mutations in the mitogen-activated protein kinase kinase kinase 1 and Harvey rat sarcoma viral oncogene homolog kinases in LCH and histiocytic sarcoma, respectively. These discoveries have refined the understanding of the histiocytoses as clonal, myeloid neoplasms driven by constitutive mitogen-activated protein kinase signaling and identified molecular therapeutic targets with promising clinical responses to rapidly accelerated fibrosarcoma and mitogen-activated protein kinase kinase inhibition. SUMMARY: Genomic analyses over the last 6 years have identified targetable kinase alterations in BRAF V600E-wildtype histiocytic neoplasms. However, despite this progress, the molecular pathogenesis and therapeutic responsiveness of non-BRAF V600E kinase alterations are still poorly defined in these disorders.
Subject(s)
Histiocytoma/genetics , Animals , Biomarkers, Tumor , Genetic Predisposition to Disease , Genomics/methods , Histiocytoma/diagnosis , Histiocytoma/metabolism , Histiocytoma/therapy , Humans , Mitogen-Activated Protein Kinases/metabolism , Molecular Targeted Therapy , Mutation , Oncogene Proteins, Fusion/genetics , Oncogene Proteins, Fusion/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Precision Medicine/methods , Proto-Oncogene Mas , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/drug effects , Treatment OutcomeABSTRACT
BACKGROUND: to describe clinical, radiologic and pathologic features of lung lesions in Birt-Hogg-Dubè syndrome (BHDS) (MIM 135150). METHOD: review of 12 patients of BHDS from 3 unrelated Italian families evaluated at GB Morgagni Hospital, Forlì, from 2005 to 2010. RESULTS: mean age (±SD) at diagnosis was 44.6 (±16) years, 8 (66%) were male. All three index cases presented with a history of recurrent pneumothorax and/or cystic lung lesions evaluated by CT scan request by referring pulmonary physicians, none were diagnosed to have BHDS at the time of initial pulmonary evaluation. One of the three cases was a middle-aged female patient with a clinical phenotype indistinguishable from lymphangioleiomyomatosis (LAM), characterized by cystic lung lesions and kidney angiomyolipoma. In one case of BHDS presenting with recurrent pneumothorax and a solitary lung nodule, surgical lung resection revealed a pulmonary histiocytoma. In one case a novel mutation of BHD gene was detected (c.771 del, exon 7). CONCLUSIONS: BHDS is associated with cystic lung disease largely under-recognized by pulmonary physicians and can mimic LAM and may be associated with lung tumor, pulmonary histiocytoma. In one case we found a novel mutation in exon 7, c.771 del (ref.seq. NM_144997.5) never reported before.
