Angiomyomatous Hamartoma of Lymph Nodes, Revisited: Clinico-pathologic Study of 21 Cases, Emphasizing Its Distinction from Lymphangioleiomyomatosis of Lymph Nodes

Publication date: Available online 9 September 2017
Source:Human Pathology
Author(s): Michelle Moh, Ankur Sangoi, Joseph T. Rabban
Angiomyomatous hamartoma of lymph nodes (AMH-LN) is an uncommon benign proliferation of smooth muscle, blood vessels, collagenous stroma and adipocytes, most commonly affecting inguinal LN. A similar constellation of cell types constitutes various members of the perivascular epithelioid cell tumor (PEComa) family, including lymphangioleiomyomatosis (LAM) which can involve LN in women. Because some LN-LAM patients have tuberous sclerosis complex (TSC) and/or other PEComa family lesions, it is clinically relevant to distinguish LN-LAM from AMH-LN. Given their similar features, however, the possibility that AMH-LN is a morphologic variant of LN-LAM merits inquiry. The dual melanocytic and myoid immunophenotype distinguishes the PEComa family from its mimics. Cathepsin K has recently emerged as a more sensitive marker for the PEComa family than HMB-45, which can be weak and focal,but cathepsin K has not been studied in AMH-LN. This study evaluated 21 AMH-LN for clinical, morphologic and immunophenotypic features of LN-LAM. None (0/21) had TSC or PEComas. Thirteen (62%) were male, unlike LN-LAM which is restricted to women. All cases exhibited intraparenchymal proliferation of variable size, thick-walled blood vessels within collagenous stroma containing a sparse to focally cellular population of haphazardly distributed smooth muscle cells. Admixed adipocytes were commonly present. None exhibited classical features of LN-LAM such as subcapsular localization, extranodal extension, intralymphatic growth, compact nests, branching lymphatic channels, plump cell shape or foamy / clear cytoplasm. None exhibited any staining for cathepsin K, HMB45, or MiTF. There is no clinical, morphologic or immunohistochemical evidence to suggest that AMH-LN is a variant of LN-LAM.



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