Superficial acral fibromyxoma

This is a newly characterised soft tissue tumour of the hands and feet with a tendency to involve the nail region. The information below is based on 37 cases.

Clinical features

Adults (range 14 to 72 years, median 46 years). M:F=2:1.

Site: great toe;12, other toes;8, fingers;13, palm; 4. 16 cases involved the nail region. The lesions were generally slow-growing and painless.

Macroscopic appearances

The tumours ranged from 0.6 to 5.0 cm (median 1.5 cm). They were soft to firm with a gelatinous or solid off-white cut surface.

Histopathology

The lesions were dermal or subcutaneous and a few involved fascia or periosteum. Cellularity was moderate, consisting of stellate or spindled fibroblast-like cells in a myxoid (n=19), myxocollagenous (n=11) or collagenous (n=7) matrix. A storiform pattern was see. Multinucleate cells were present (n=19). Five tumours showed moderate or pronounced nuclear pleomorphism. Five tumours showed mitoses, up to 7 per 50 HPF. Most cases contained mast cells and some a mild lymphocytic infiltrate. The margins were pushing (n=22) or infiltrative (n=15).

Immunohistochemistry

 

CD34

21/23

EMA

18/25

CD99

11/13

S-100

1/23

HMB-45

0/?27

SMA

0/?27

muscle-specific actin

0/?27

desmin

0/?27

GFAP

0/?27

Keratins (AE1/AE3, LP34)

0/?27 (rare entrapped fibrous cells stained)

   

 

 

Ultrastructure

Differential diagnosis

See: Differential diagnosis of cutaneous and subcutaneous myxoid lesions

Management

Complete excision, in view of uncertain behavior, especially in the cases with pleomorphism or mitoses.

Prognosis

May recur locally. No metastases reported.

References

Fetsch, J. F., Laskin, W. B., Miettinen, M. Superficial acral fibromyxoma: a clinicopathologic and immunohistochemical analysis of 37 cases of a distinctive soft tissue tumor with a predilection for the fingers and toes. Hum Pathol 2001;32:704-714.

This page last revised 8.11.2001.