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 MagnificationLow 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 ReticulohistiocytomaHigher 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 MagnificationHigh 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 ReticulohistiocytomaThis 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
• Overlying epidermis may show atrophy/thinning
image Often grenz zone separating infiltrate from epidermis

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

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