An Atypical Angiomyomatous Hamartoma With Unexplained Hepatosplenomegaly

Angiomyomatous hamartoma (AMH) of the lymph node is an extremely uncommon vascular disorder of unknown etiology, first described by Chan and colleagues in 1992.^1-3 Angiomyomatous hamartoma particularly involves inguinal and femoral lymph nodes, with few cases reported in the cervical, popliteal, and submandibular lymph nodes.¹ Angiomyomatous hamartoma can occasionally be associated with edema of the ipsilateral limb. To the authors’ knowledge, to date only 18 cases of AMH have been reported.⁴

Case Presentation

A 40-year-old white man started to have a left inguinal and scrotal pain along with left thigh swelling at age 22 while serving in the U.S. Army.

An abdominal Doppler ultrasound did not show any evidence of portal hypertension. A thoraco-abdomino-pelvic computed tomography (CT) scan showed bilateral axillary, subcarinal (Figure 1), mesenteric and retroperitoneal (Figure 2), and left inguinal (Figure 3) lymphadenopathy. Excisional biopsy of a 3.5 x 2.5 x 1.5 cm left inguinal lymph node was performed, and histopathology showed extensive smooth muscle and vascular proliferation replacing most of the lymph node (Figure 4), a finding consistent with AMH. A trichrome staining (Figure 5) and immunohistochemical study for smooth muscle actin (Figure 6) were performed and supported the diagnosis. Due to persistent pain in the scrotal area, the patient underwent a left spermatic cord denervation. Currently, the patient has persistent left thigh swelling. His condition remains stable with a regular follow-up CT scan showing unchanged lymphadenopathy.

Discussion

Angiomyomatous hamartoma is a rare, primary vascular tumor of the lymph nodes occurring almost exclusively in the inguinal and femoral lymph nodes and occasionally associated with edema of the ipsilateral limb.¹ A few cases with popliteal and cervical lymph node involvement have been reported.¹ There are no prior reports of cases with either generalized adenopathy or hepatosplenomegaly.

The histopathogenesis of AMH remains unclear. Chan and colleagues first reported this distinct clinicopathologic entity in 1992 as a primary vascular tumor of the lymph node.^1-3 The hamartomatous nature of the disease was postulated by the authors on the basis of a disorganized growth pattern of smooth muscle cells and blood vessels noted on pathology.^2,3 The AMH could represent a localized malformation in a congenitally damaged lymphatic vessel system.⁵ Other hypothesis suggests lymphedema as a possible etiology of AMH through continuous stimulation of lymphatic vessels, which triggers vasoproliferation and eventually the vascular transformation of the lymph nodes.⁵

Differential diagnoses of AMH include nodal lymphangiomyomatosis, which is most prevalent in women, particularly presenting with thoracic and intra-abdominal lymph nodes and plumper HMB45 (human melanoma black 45) -positive tumor cells⁶; leiomyomato

Treatment is either conservative or surgical, depending on clinical judgment. This is only the 19th case of AMH reported so far in the literature and the fifth reported case in which the patient presented with ipsilateral lymphedema of the limb. Importantly, it is the first reported case with generalized (axillary, subcarinal, mesenteric, inguinal and retroperitoneal) lymphadenopathy and unexplained hepatosplenomegaly.

Conclusion

Angiomyomatous hamartoma of the lymph nodes is an exceedingly rare diagnosis but should be considered when evaluating patients with lymphatic tumors. This patient remains relatively asymptomatic and on observation at this time and seems to have more extensive disease than prior reports in the literature.