Solitary subcutaneous mucinosis surrounded by bizarre-shaped, factor XIIIa-positive cells with intranuclear vacuoles

Myxomas and Angiomyxomas of the Orbit

PURPOSE

To report clinical and histopathologic features and biologic behavior of orbital myxomas and angiomyxomas.

DESIGN

Noncomparative retrospective case series.

PARTICIPANTS

Patients with histopathologic diagnoses of orbital myxoma or angiomyxoma.

METHODS

Clinical metadata and features were obtained from the medical record. Neoplasms were studied by routine histopathology, special stains, and immunohistochemistry.

MAIN OUTCOME MEASURES

Final diagnosis, based on histopathology, special stains, and immunohistochemistry, and clinical course from analysis of metadata and clinical features.

RESULTS

Three myxomas and 3 angiomyxomas were identified in 5 males and 1 female. Median age at presentation was 56 years (range, 4-69), with a follow-up ranging from 6 months to 8 years. Two angiomyxomas occurred in children ages 4 and 7 years whose tumors were locally aggressive and recurred. Recurrence also complicated one case of myxoma after incomplete excision. Pathologically, the tumors were poorly circumscribed. Histopathology showed them to be hypocellular, containing stellate and spindled cells in an abundant, loose, myxoid stroma rich in hyaluronic acid. Small blood vessels were rare in myxomas but abundant in angiomyxomas. Tumor cells were frequently immunoreactive for vimentin, CD34, and factor XIIIa.

CONCLUSIONS

Myxomas rarely involve orbital tissue, and no angiomyxomas of the region have been previously reported. Angiomyxomas in children may be aggressive. Vascularity and bone involvement appear to be important prognostic features for recurrence. Complete resection with a margin of healthy tissue appears to be the treatment of choice. Tumor cell immunopositivity for vimentin, CD34, and factor XIIIa may assist in the histopathologic diagnosis.

Adult variant of self-healing papular mucinosis in a patient with rheumatoid arthritis: predominant proliferation of dermal dendritic cells expressing CD34 or factor XIIIa in association with dermal deposition of mucin

According to a recent classification, self-healing papular mucinosis (SHPM) is a subtype of papular mucinosis (also known as lichen myxedematosus), which is in turn a type of idiopathic localized cutaneous mucinosis. SHPM tends to occur in children, but there have been a few reports of an adult type. We report a 70-year-old Japanese woman who presented with reddish, rice-kernel-sized papules of a few days' duration on her right arm. She had a 25-year history of rheumatoid arthritis, which had been well treated with a low dose of corticosteroid as well as some other medications. No paraproteinemia or thyroid dysfunction were observed. The eruptions spontaneously resolved within 2.5 months of onset. Histological findings showed a well-circumscribed mucinous stroma surrounded by dermal mesenchymal cells, such as fibroblast-like cells in the middle of the dermis. Immunohistochemically, these cells were positive only for vimentin on the mucinous lesion. On the circumference of the mucinous lesion, these cells expressed either CD34 or factor XIIIa (FXIIIa). Because vimentin was common to dermal mesenchymal cells, we defined the cells expressing CD34 or FXIIIa, except for vimentin+ cells lacking CD34 or FXIIIa, as dermal dendritic cells (DDC). The findings of the present case suggest that CD34+ or FXIIIa+ DDC and tryptase-positive mast cells on the perilesional area in combination with vimentin+ cells on the mucinous lesion might have given rise to the dermal deposition of mucin in our case. These cells, which are possibly activated in an autoimmune manner associated with rheumatoid arthritis, might play important roles in the development of dermal deposition of mucin in SHPM.

Reticular erythematous mucinosis syndrome with an infiltration of factor XIIIa+ and hyaluronan synthase 2+ dermal dendrocytes

We report a patient with reticular erythematous mucinosis (REM) syndrome. Content of hyaluronan in lesional skin was approximately 2.9-fold higher than in the patient's uninvolved skin, but its synthetic activity in fibroblasts explanted from lesional skin remained unchanged. Immunohistochemical study using antifactor XIIIa (anti-FXIIIa) antibody demonstrated that the number of FXIIIa+ cells in the lesional skin was significantly increased compared with those in the patient's uninvolved skin and in normal control skin samples (P < 0.01). As hyaluronan is considered to be synthesized by hyaluronan synthase (HAS), which is composed of three genetically distinct isoforms (HAS1, HAS2 and HAS3), the cells responsible for the accumulation of hyaluronan in lesional skin were immunohistochemically examined using antibodies for HAS1, HAS2 and HAS3. The specific antibody for HAS2 was found to react with some populations of FXIIIa+ cells in the involved skin, and the number of HAS2+ cells was significantly increased in the involved skin (P < 0.01). The results suggest that accumulation of hyaluronan in REM may be related to populations of FXIIIa+/HAS2+ dermal dendrocytes rather than to dermal fibroblasts.