Lymph nodes & spleen, nonlymphoma

• A rare, benign parenchymal lesion composed of disorganized red pulp without well formed white pulp

• Postulated to represent a malformation, vascular neoplasm or posttraumatic reactive lesion
• Debate exists if hamartoma is a true neoplasm (Mod Pathol 2011;24:108)
  • Human androgen receptor assay (HUMARA) suggests a polyclonal lesion
  • However, a single case showed dic(16;21)(p13.1;p11.2)del(16)(q11.1) with gains of several chromosomes and monosomy 21 (Cancer Genet Cytogenet 2005;157:160)

• Usually an incidental finding in an asymptomatic individual
• May infrequently present with symptoms related to mass effect, such as pain or a palpable mass
• Can present with hematologic complications associated with hypersplenism, such as thrombocytopenia and anemia (Am J Case Rep 2022;23:e937195)
• Splenic rupture is rare
• Rare cases associated with tuberous sclerosis and Alagille syndrome (Fetal Pediatr Pathol 2014;33:216)

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Contributed by Nadine S. Aguilera, M.D. and Emily Gardner, M.D.


Images hosted on other servers:

Contributed by Nadine S. Aguilera, M.D.

• Spleen, splenectomy:
  • Splenic hamartoma (see comment)
  • Comment: Histopathologic examination of the [size] cm mass revealed a vaguely demarcated area showing red pulp without white pulp. Immunohistochemical staining was performed on block [X]. CD8 stains the endothelium of normal splenic sinuses in the normal splenic tissue as well as the disorganized sinuses in the hamartoma. CD20 and CD3 staining revealed a lack of B cells and rare T cells, respectively, within the hamartoma. Normal white pulp stains with CD20 with peripheral CD3 positive T cells. Kappa and lambda RNA staining revealed polytypic plasma cells throughout the tissue, without monotypic staining in the normal splenic white pulp. The findings support a diagnosis of splenic hamartoma. Extramedullary hematopoiesis is present and commonly found in splenic hamartomas.

• Splenic hemangioma:
  • Cystically dilated and blood filled spaces, lined by a single layer of bland flat endothelial cells
  • Does not contain cords and sinuses
  • Vascular spaces are separated by thin fibrous septa
  • Mitoses are absent
  • CD34+, CD31+, factor VIII+, ERG +, CD8-, CD68- and D2-40-
• Littoral cell angioma:
  • Benign neoplasm unique to the spleen
  • Pleomorphic vascular spaces ranging from slit-like to dilated cystic spaces
  • Spaces commonly filled with papillary projections lined by tall / plump endothelial cells
  • Tall lining cells: CD31+, CD68+, CD21 focal+, CD8- and CD34-
• Sclerosing angiomatoid nodular transformation of the spleen (SANT):
  • Benign vascular lesion of uncertain etiology, likely reactive
  • Predominantly affects adults
  • Typically presents as a single mass with a central stellate scar
  • Multiple angiomatoid nodules containing a mixture of capillaries, sinusoids and veins
  • Interspersed fibrosclerotic stroma
  • Endothelial cells can be prominent
• Peliosis:
  • Can present as an isolated finding but most commonly presents in association with peliosis hepatis
  • Multiple blood filled spaces that are haphazardly scattered in the red pulp
  • Spaces are lined by inconspicuous endothelial cells; however, endothelial cells may be completely absent
  • Key differentiating factor is the presence of white pulp
  • If an endothelial lining is present: CD34+, factor VIII+ and CD31+

Which of the following features is seen in splenic hamartoma?

1. Anastomosing vessels
2. Dilated sinuses
3. Red pulp without white pulp
4. Sclerosing nodules and entrapped vessels

C. Red pulp without white pulp. This is an essential feature of splenic hamartoma. Answer A is incorrect because anastomosing vessels are seen with splenic angiosarcoma. Answer B is incorrect because dilated sinuses are seen with congestive splenomegaly. Answer D is incorrect because sclerosing nodules and entrapped vessels are seen in sclerosing angiomatoid nodular transformation of the spleen (SANT).

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Reference: Hamartoma