Asymptomatic plantar nodules in a 1-year-old healthy girl

A healthy 1-year-old girl presented to our dermatology clinic with bilateral asymptomatic planter nodules that were noticed by her parents at 1 month of age. There was no family history of similar lesions. On examination, there were bilateral, soft, skin-colored, nontender, mobile nodules over the medial plantar surface of both feet measuring around 1.5 × 0.5 cm (Fig 1). Ultrasound examination of the plantar surfaces found increased subcutaneous focal fatty deposition at the site of skin nodules. The lesions were hyperechoic with no increase in vascularity (Fig 2). Histologic examination found fibroadipose tissue encircling eccrine glands in the dermis (Fig 3).

Fig 1.

Fig 2.

Fig 3.

Question 1: What is the most likely diagnosis?

• A.Juvenile plantar fibromatosis
• B.Calcified nodules
• C.Piezogenic papules
• D.Precalcaneal congenital fibrolipomatous hamartoma (PCFH)
• E.Nevus lipomatosus superficialis

Answers:

• A.Juvenile plantar fibromatosis – Incorrect. In juvenile plantar fibromatosis, the lesions are generally asymptomatic, unilateral, and indurated on palpation. Usually, this condition develops in the second or third decade of life. On histopathology, it is characterized by the presence of fibrous tissue attached to the plantar fascia.¹
• B.Calcified nodules – Incorrect. The common cause of calcified nodules is frequent needle insertion in the heel for drawing blood during neonatal period. They are usually painful and may be dystrophic in nature.¹
• C.Piezogenic papules – Incorrect. Piezogenic papules are pressure induced and appear only upon standing. The lesions are usually located on the lateral aspect of bilateral heels. They are caused by fat herniation into the dermis.¹ Physical strain is an important risk factor; thus, the term piezogenic describes the pressure-induced changes in these lesions. The affected individuals include obese patients, marathon runners, and patients whose occupations require them to stand for a long time.¹
• D.PCFH – Correct. PCFH is a benign skin disorder characterized by asymptomatic nodules on the plantar surface of the feet. The skin lesions in PCFH are classically bilateral, solitary, skin colored, nonpruritic, and nontender nodules in the medial plantar aspect of the foot. These nodules can present at infancy or during the first few months of life. This condition was first defined by Larralde de Luna et al.² in 1990, and it was originally named pedal papules in the newborn. Several names have been used to describe PCFH including infantile pedal papules, congenital adipose plantar nodules, and anteromedial plantar nodules of the heel in childhood.³
• E.Nevus lipomatosus superficialis – Incorrect. The lesions typically appear on the hip or thigh in nevus lipomatosus superficialis. It is characterized by ectopic adipose tissue in the dermis.¹

Question 2: Which of the following features is a common characteristic of lesions in precalcaneal congenital fibrolipomatous hamartoma?

• A.Erythematous
• B.Malignant
• C.Bilateral
• D.Hereditary
• E.Painful

Answers:

• A.Erythematous – Incorrect. The lesions in PCFH are skin-colored nodules without overlying erythema.³
• B.Malignant – Incorrect. PCFH is characterized by benign skin lesions. To date, no reports of malignancies have been stated in the literature.³
• C.Bilateral – Correct. Bilateral nodules are the typical presentation of PCFH as in our case. Nonetheless, few cases have been reported with unilateral involvement.³
• D.Hereditary – Incorrect. The etiology of PCFH is still undetermined; however, a few hypotheses have been proposed. One hypothesis suggests that PCFH might result from incomplete regression of fetal tissue. Another hypothesizes the cause of PCFH is secondary to fat herniation through plantar fascia defects. A final one implies that PCFH occurs because of an underlying genetic mechanism which could be X-linked inheritance or autosomal dominant although sporadic PCFH in otherwise healthy children is more common.³
• E.Painful – Incorrect. PCFH is generally asymptomatic, and it is commonly an incidental finding by the parents.³

Question 3: Which of the following statements is true regarding this diagnosis?

• A.Skin biopsy is rarely indicated.
• B.The natural history of these skin lesions is easily predictable.
• C.Surgical excision is usually the treatment of choice.
• D.The affected individuals are mostly immunocompromised.
• E.The nodules exclusively occur in the precalcaneal region.

Answers:

• A.Skin biopsy is rarely indicated – Correct. With full knowledge of PCFH, it can be diagnosed clinically. Invasive investigations such as skin biopsies are generally avoided.¹
• B.The natural history of these skin lesions is easily predictable – Incorrect. Because PCFH is presumably underreported, it is challenging to determine its clinical course. Some cases regress spontaneously after 2 to 3 years of their onset while others persisted without changes in their size or nature.^2,4 In our patient, the lesions have not changed in size since their onset.
• C.Surgical excision is usually the treatment of choice – Incorrect. Treatment for PCFH is generally not required. Once recognized, parents should be reassured about the benign nature of this condition.⁴
• D.The affected individuals are mostly immunocompromised – Incorrect. PCFH commonly affects otherwise healthy children with no impact on daily activities such as walking.⁴
• E.The nodules exclusively occur in the precalcaneal region – Incorrect. Several names have been proposed for PCFH with the most recent being cutaneous fibrolipomatous hamartoma. The latter carries a broader nomenclature because there are some atypical reported cases involving retro-calcaneal areas as opposed to the classic presentation.⁵