Page 62 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-35 Integumentary System

RETICULOHISTIOCYTOMA

Reticulohistiocytomas, also called solitary epithelioid Multicentric reticulohistiocytomas. Coral
histiocytomas, are conglomerations of large eosino- red papules on the fingers. Can be associated
philic histiocytes within the dermis. The cytoplasm of with severe disabling arthritis.
these cells has been described as “glassy” in appearance.
Reticulohistiocytomas are a subset of the histiocytoses
group of diseases. In contrast to the other histiocytoses,
patients with reticulohistiocytoma have normal lipid
levels.
Reticulohistiocytomas can occur as a solitary growth
or as multiple growths in a condition known as multi-
centric reticulohistiocytosis. The solitary variant is Organs Involved in Reticulohistiocytoma
more often seen. On histopathological examination, the
two clinical variants are identical in nature. Multicen- Inflammatory arthritis (hands, knees, shoulders)
tric reticulohistiocytosis is a rare disease with systemic Lungs
involvement. It can often be a marker of internal malig- Bone marrow
nancy, and patients are afflicted with a severe arthritis. Eyes
Clinical Findings: Solitary lesions are typically small, Heart
firm dermal nodules ranging from 1 to 2 cm in diameter.
They are usually asymptomatic. Their coloration may Associated Autoimmune Diseases and Malignancy
vary, but most often they are slightly pink to red-brown.
They are found most commonly on the head and neck Systemic lupus erythematosus Lymphoma
region of the body but have been described in all loca- Breast cancer Lung cancer
tions. They occur with similar frequency in males and Colon cancer
females and have no age or race predilection. Primary biliary cirrhosis
Multicentric reticulohistiocytosis is unique in that it
occurs in an older population, with a higher percentage
of females affected. The number of lesions is in the
hundreds to thousands. The multiple reticulohistiocy-
tomas found in this condition are most often localized
to the dorsal aspect of the hands and to the face. A
distinctive finding is that of small papules along the
lateral and proximal nail folds. This finding has been
described as “coral beading,” and it is highly
specific for multicentric reticulohistiocytosis. These
patients also have a severe arthropathy, and this diag-
nosis should lead one to look for an underlying malig-
nancy. The arthropathy almost always affects the
interphalangeal joints, particularly the distal interpha-
langeal joints. Multicentric reticulohistiocytosis is
believed to be a paraneoplastic condition in up to 25%
of the cases. The type of malignancy is variable, with
no predominant type more prevalent than any other.
For this reason, age-appropriate cancer screening
is recommended. In about one third of patients with
multicentric reticulohistiocytosis, the joint symptoms
precede the growths; in one third, they appear at the
same time; and one third of the patients develop only
clinically minor or no arthropathy. This arthropathy is
a severe inflammatory arthropathy that is symmetric
and polyarticular. A mutilating arthritis may develop, Low power. A diffuse dermal infiltrate of “ground- High power. A few multinucleated giant cells
sometimes very quickly. Early recognition and treat- glass” histiocytes are seen within the tumor.
ment has helped decrease the progression into severe
mutilating arthritis. This truly is a multisystem organ
disease. Many patients have cardiac involvement, and
almost all organ systems have been reported to be
affected, some with fatal outcomes. appearance of the cytoplasm. Multinucleate giant cells Patients with multicentric reticulohistiocytosis require
Pathogenesis: Multicentric reticulohistiocytosis and are always seen. They contain more than three nuclei, systemic therapy. Screening and constant vigilance
solitary reticulohistiocytoma are believed to represent which can be arranged in many variations. The cells stain for an underlying malignancy is required in all cases.
a rare disorder of histiocytes. The cause of the histio- with the immunohistochemical stains CD45 and CD68, Corticosteroids, methotrexate, hydroxychloroquine,
cytic proliferation is unknown. but do not stain with S100. On electron microscopy, no and cyclophosphamide have all been used. Anti–tumor
Histology: The tumor shows a well-circumscribed Langerhans cells are found in the infiltrate. necrosis factor (anti-TNF) agents have been used. The
dermal infiltrate without a capsule. The infiltrate is made Treatment: Solitary reticulohistiocytomas are cured goals are to prevent or suppress the arthropathy and to
up almost entirely of histiocytes with a “ground-glass” with a simple elliptical excision. They rarely recur. screen for malignancy.

48 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS