Reticulohistiocytoma

 Different clinical features: Multiple cutaneous lesions, may have joint &/or internal organ involvement in multicentric cutaneous reticulohistiocytosis



• Juvenile xanthogranuloma

• Langerhans cell histiocytosis

• Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy)



image
Solitary Reticulohistiocytoma at Low Magnification
Low magnification shows a nodular dermal infiltrate composed of large, eosinophilic-staining histiocytic cells, associated with mixed inflammatory infiltrate, including many lymphocytes and eosinophils.


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Solitary Reticulohistiocytoma
Higher magnification shows a population of large histiocytic-appearing cells with dense, eosinophilic-staining cytoplasm image, associated with an infiltrate, including many lymphocytes and eosinophils image.

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Solitary Reticulohistiocytoma at High Magnification
High magnification shows the large, eosinophilic-staining histiocytic cells with dense, glassy cytoplasm and focal emperipolesis image of lymphocytes. Note the mixed background inflammatory infiltrate, including many eosinophils image.

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S100 Immunohistochemistry in Reticulohistiocytoma
This case showed greater S100 staining than usual, although it is relatively weak and mostly cytoplasm. Entrapped dendritic cells show much stronger staining.


TERMINOLOGY


Synonyms




• Solitary cutaneous reticulohistiocytoma

• Reticulohistiocytic granuloma

• Giant cell reticulohistiocytoma


Definitions




• Proliferation of histiocytes with abundant dense, glassy-appearing eosinophilic cytoplasm


ETIOLOGY/PATHOGENESIS


Environmental Exposure




• May be related to stimuli, such as insect bites, infection, trauma, or ruptured folliculitis or cyst in some cases


CLINICAL ISSUES


Epidemiology




• Incidence
image Rare tumor

• Age
image Usually occurs in adults > 40 years old
– However, some cases have been reported in adolescents

• Sex
image M:F = 1:1

• Ethnicity
image Most cases occur in Caucasians


Site




• Usually head and neck region, including mucosal sites
image However, may present at almost any cutaneous site


Presentation




• Skin papule or nodule
image Usually single lesion, but several may be present in some cases

• Firm, rapidly growing lesion

• Usually appear as red-brown or yellow-brown

• May be preceded by trauma in some cases

• Lack of systemic symptoms, including fever, weight loss, or weakness (which may be seen in multicentric reticulohistiocytosis)


Treatment




• Surgical approaches
image Complete conservative excision is curative

– Usually not required, unless lesion is very large or fails to resolve


Prognosis




• Excellent; lesions often involute spontaneously
• No definite relationship with more aggressive multicentric reticulohistiocytosis

image However, multiple skin lesions should suggest possibility of generalized cutaneous reticulohistiocytosis


MACROSCOPIC


General Features




• Dermal-based, nodular, well-circumscribed, but unencapsulated, lesion


Size




• Lesions typically range in size from 0.5-2.0 cm


MICROSCOPIC


Histologic Features




• Dermal-based nodular proliferation of large mononuclear and multinucleated histiocytes
image Cells show characteristic abundant glassy/hyalinized-appearing eosinophilic cytoplasm

image Some cells may show finely granular cytoplasm

image Occasional Touton-type giant cells containing lipid may be present but not prominent

image Cytologic atypia is usually minimal, and mitoses are few and nonatypical

image No infiltrative features are present

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Reticulohistiocytoma
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