Lymph nodes & spleen, nonlymphoma

Spleen-vascular tumors

Hamartoma


Editorial Board Member: Anamarija M. Perry, M.D.
Deputy Editor-in-Chief: Patricia Tsang, M.D., M.B.A.
Selveras Zayed, M.B.B.Ch., B.A.O.
Nadine Aguilera, M.D.

Last author update: 14 August 2023
Last staff update: 14 August 2023

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed Search: Hamartoma

Selveras Zayed, M.B.B.Ch., B.A.O.
Nadine Aguilera, M.D.
Page views in 2023: 3,617
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Cite this page: Zayed S, Aguilera N. Hamartoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/spleenhamartoma.html. Accessed April 15th, 2024.
Definition / general
  • A rare, benign parenchymal lesion composed of disorganized red pulp without well formed white pulp
Essential features
  • Circumscribed nodule in spleen
  • Composed of disorganized red pulp and absent white pulp
  • CD8 confirms the presence of disorganized sinuses
Terminology
  • Also called splenoma
ICD coding
  • ICD-11: 3B81.0 - tumor-like conditions of spleen
Epidemiology
  • Uncommon
  • Occurs in all age groups and exhibits no sex predilection
Sites
  • Spleen
Pathophysiology
  • 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)
Etiology
  • Unknown
Clinical features
  • 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)
Diagnosis
  • Radiology (ultrasound, CT or MRI) demonstrates the presence of a solid mass
  • Splenic biopsy (FNA, needle biopsy)
  • Splenectomy
  • Reference: Am J Case Rep 2022;23:e937195
Laboratory
Radiology description
  • Increased blood flow on color Doppler ultrasound in the splenic lesion
  • Most appear on MRI as isointense lesions on T1 weighted image and heterogeneously hyperintense on T2 weighted image
Radiology images

Images hosted on other servers:
Heterogenous enhancing splenic lesion on CT

Heterogenous enhancing splenic lesion on CT

Color Doppler showing dotted blood flow signals in mass

Color Doppler showing dotted blood flow signals in mass

T1 and T2 weighted MRI of splenic mass

T1 and T2 weighted MRI of splenic mass

Isointense mass

Isointense mass

Prognostic factors
  • Excellent prognosis
Case reports
Treatment
  • Splenectomy or partial splenectomy is curative
Gross description
Gross images

Contributed by Nadine S. Aguilera, M.D. and Emily Gardner, M.D.
Solitary well circumscribed mass

Solitary well circumscribed mass

Hamartoma with similar texture and color as the spleen

Hamartoma with similar texture and color as the spleen



Images hosted on other servers:
Nodule of increased stiffness

Nodule of increased stiffness

Resected spleen

Resected spleen

Microscopic (histologic) description
  • Benign vascular proliferation composed of disorganized red pulp elements (sinuses and cords) only (Mod Pathol 2011;24:108)
  • Unencapsulated with borders that may be ill defined microscopically (Semin Diagn Pathol 2019;36:16)
  • Scant fibrous trabeculae
  • No well formed white pulp
  • Usually lacks cytologic atypia
  • CD8+ sinuses present
  • Additional features may include focal sclerosis, calcifications, hemorrhage, peliosis, plasmacytosis, extramedullary hematopoiesis, eosinophils and mast cells
  • Rarely, scattered bizarre cells featuring ill defined cytoplasm and irregular nuclei with vesicular chromatin that are likely dendritic or stromal myoid in nature are identified
Microscopic (histologic) images

Contributed by Nadine S. Aguilera, M.D.
Splenic hamartoma and uninvolved spleen

Splenic hamartoma and uninvolved spleen

Red pulp Red pulp

Red pulp


CD8 stain

CD8 stain

CD34 stain

CD34 stain

CD21 stain

CD21 stain

CD68 stain

CD68 stain

Cytology description
  • Nonspecific
    • No atypia or mitosis
    • Stromal cells can be bizarre
Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • 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.
Differential diagnosis
  • 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+
Additional references
Board review style question #1

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
Board review style answer #1
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
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