Superficial Acral Fibromyxoma involving the nail's apparatus. Case report and literature review

Abstract

Superficial Acral Fibromyxoma is a rare tumor of soft tissues. It is a relatively new entity described in 2001 by Fetsch et al. It probably represents a fibrohistiocytic tumor with less than 170 described cases. We bring a new case of SAF on the 5th toe of the right foot, in a 43-year-old woman. After surgical excision with safety margins which included the nail apparatus, it has not recurred (22 months of follow up). We carried out a review of the location of all SAF published up to the present day.

INTRODUCTION

Superficial Acral Fibromyxoma (SAF) is a rare tumor of soft tissues with slow growth and acral location. It has a benign behavior, but it may persist or recur if not properly treated.

CASE REPORT

We present a 43-year-old woman, without any known allergies whose personal history reports beta thalassemia. She referred having had cutaneous changes not associated with any trauma for 8 years, consisting of swelling, partial nail loss and distal ulcerations with occasional bleeding on the 5^th toe of the right foot. When the patient wore open shoes it was painless; however, it hurt and bled when she wore closed shoes. Upon examination, the distal end of the 5^th toe presented a central ulcer with blood remains and partial onycholysis (Figure 1A).

FIGURE 1.

A: Loss of the distal end of the 5th toe of the right foot and partial onycholysis; B: Fusiform cell proliferation in a myxoid stroma (HE, x100); C: Fusiform cells show cytoplasmic positivity to CD34 (PAP, x200); D: Image after excision. The macroscopic part of the tumor along with nail apparatus can be seen

Antero-posterior and oblique X-rays were requested of both feet, which showed subluxation of the distal phalanges of the 5^th toes without signs of bone infiltration and a diagnostic biopsy was performed.

Histological results showed neoplastic dermal proliferation of fusiform cells without any relevant atypia, immersed in a myxoid stroma with collagenized areas and a prominent vascular weave (Figure 1B). Immunohistochemical studies reported positive results for CD34 and negative for S100, AME and AML (Figure 1C). The proliferation index, valued with Ki67 was low (less than 1%). These findings led to the diagnosis of Superficial Acral Fibromyxoma.

The subsequent therapeutic approach included complete removal of the tumor as well as the nail in order to avoid recurrence.

Histological examination of the surgical piece was similar to the previously described. The tumor was extirpated with wide margins, including the nail matrix, respecting the distal phalanx (Figure 1D). Resection margins were reported as tumor-free.

After a 22-month follow-up there was no recurrence of the tumor.

DISCUSSION

Superficial Acral Fibromyxoma (SAF) is a rare tumor of soft tissues, with slow growth and located in the subungual or periungual region of the hands and feet^1-7 (Table 1). However, the heel, palm and ankle can also be affected.⁵ It affects young adults (mean age 43 years old), with higher frequency in men than in women in a 2:1 proportion. It is a relatively new entity described in 2001 by Fetsch et al.⁴ It probably represents a fibrohistiocytic tumor with less than 170 described cases (SAF series and isolated case reports).²

TABLE 1.

Summary of all published cases and locations of SAF

References	Cases described	Location	N° Cases	References	Cases described	Location	N° Cases
Fetsch JF et al.	37	Toes	20	Tardío JC et al.	4	Big toe	1
		Fingers	13	Am J Dermatopathol.		Middle finger	1
Hum Pathol. 2001;32:704-14.		Palm	4	2008;30:43-5.		Palm of hand	1
						Thumb of hand	1
Kazakov DV et al.	2	Toes	2	Luzar B and Calonje E.	14	Big toe	8
Dermatology. 2002;205:285-8.				Histopathology. 2009;54:375-7.		¿	6
Meyerle JH et al.	1	Subungueal index finger	1	Pasquinelli G et al.	1	Index finger	1
J Am Acad Dermatol. 2004;50:134-6.				Ultrastruct Pathol. 2009;33:293-301.
André J et al.	1	Great toe-nail	1	Wang QF et al. Zhonghua	1	Middle finger	1
Am J Dermatopathol. 2004;26:472-4.				Bing Li Xue Za Zhi. 2009; 38:682-5.
Quaba O et al.	1	Ring finger	1	Goo J et al. Ann Dermatol. 2010; 22:110-3.	1	Subungueal index finger	1
Br J Plast Surg. 2005;58:561-4.
Abou-Nukta F et al.	1	Nail of the thumb	1	Chattopadhyay M et al.	1	Subungueal index finger	1
J Hand Surg Br. 2006;31:619-20.				Clin Exp Dermatol. 2010;35:807-9.
Oteo -Alvaro A et al.	1	Toe	1	Cogrel O et al. Ann	3	Great toe	1
Arch Orthop Trauma				Dermatol Venereol.		Second Toe	1
Surg. 2008;128:271-4.				2010; 137: 789-93.		Finger	1
Misago N et al.	1	Tip of big toe	1	Fanti PA et al.	12	Toes	¿
J Eur Acad Dermatol Venereol. 2008;22:255-7.				G Ital Dermatol Venereol. 2011;146:283-7.		Fingers	¿
Varikatt W et al.	2	Tip of index finger	2	Messeguer F et al.	1	Index finger	1
Skeletal Radiol. 2008;37:499-503.				Actas Dermosifiliogr. 2012;103:67-9.
Al-Daraji WI et al.	32	Toes	15	Ben Brahim E et al.	1	Toe	1
J Cutan Pathol. 2008;35:1020-6.		Fingers	13	Tunis Med. 2012;90:340-1.
		Heel	4
Al-Daraji WI et al.	2	Subungueal big toe	1	Wakabayashi Y et al.	1	Great toe	1
Dermatol Online J. 2008;28:14-27.		Index finger	1	Acta Dermatovenerol Croat. 2012;20:263-6.
Prescott RJ et al.	41	Toes	29	Wei C et al. Eplasty.	1	Thumb	1
Br J Dermatol. 2008;159:1315-21.		Fingers	11	2013;13:ic13.
		Palm	1

Pain is not usually mentioned. Ungual involvement may be present. Only one case has been associated with previous trauma. X-rays rarely show bone alterations.^1,8

Histologically, it is a well delimited, non-encapsulated dermal tumor that may extend towards the hypodermis. It is composed of a proliferation of cells from a fibroblastic line usually accompanied by many mast cells. The presence of a myxoid stroma with a rich vascular weave is very noticeable. Epidermis hyperplasia with hyperkeratosis is also frequent. CD34 positivity is characteristic but CD10, CD99, EMA, and nestin immunoreactivity are also common. Negative results for neural and muscular differentiation markers (S-100, HMB-45, SMA, desmin, actin), cytokeratin and apolipoprotein D are expected.^{1-3, 9,10}

Although it is an infrequent event, it must be included in differential diagnosis of tumors present on the fingers and toes.^1-7 Differential diagnosis considerations are summarized in chart 1.

Chart 1.

Differential Diagnosis of Superficial Acral Fibromyxoma

CD34+ Neoplasias	CD34- Neoplasias	Other lesions
Dermatofibrosarcoma protuberans	Giant cell tumor of tendon sheath	Fibroma of tendon sheath
Superficial angiomyxoma	Glomus tumor	Onychocryptosis
Myxoid neurofibroma	Sclerosing perineuroma	Cutaneous muxoma
Sclerosing fibroma	Benign fibrous histiocytoma
Acral myxoinflammatory	Acral fibrokeratoma
Spindle cell lipoma

SAF has a benign behavior but may persist or recur if not properly treated.^7,8 Thus complete removal and follow-up is recommended. Up to this date, malignization has not been described.

In conclusion, this is the description of a rare case of Superficial Acral Fibromyxoma on the nail apparatus of a 43-year-old woman. There are less than 170 published cases. It is a benign tumor with slow growth and, although rare, it should be considered in differential diagnosis of acral lesions. Surgery is curative but requires adequate margins due to the high risk of recurrence. Malignization has never been described.