Folliculocystic and collagenous hamartoma of tuberous sclerosis complex, not always a single cutaneous lesion

Abstract

Folliculocystic and collagenous hamartoma (FCCH) is a rare cutaneous manifestation characterized by the presence of single plaques studded with comedo-like openings and cysts. Although its pathophysiology is still unknown, it has generally been described in men with tuberous sclerosis complex (TSC). We report a case of a one-year-old child with two FCCH in the abdominal wall associated with TSC. In our case, a TSC2 mutation was identified.

Folliculocystic and Collagenous Hamartoma

“…The hallmark histopathological findings of FCCH are abundant thick, hyaline, eosinophilic, collagen bundles in the dermis, concentric perifollicular fibrosis and keratin-filled infundibular cysts with dilated openings. [ 1 2 3 4 5 ] All except perifollicular fibrosis were demonstrated in our patient. Although increased dermal collagenisation is an attribute shared by FCCH, angiofibromas, FCP and shagreen patches, thus representing a histopathological spectrum, features such as infundibular cysts and perifollicular fibrosis are unique to FCCH.…”

“…It appears at birth or during infancy, commonly in males, over the scalp, abdomen, lumbar region, thighs, and face. [ 1 2 3 4 5 ] Although our patient developed FCCH at a later age and lacked cystic protuberances, the prominent comedonal openings draining keratinous material were suggestive of FCCH. Of the 14 reported cases (including ours), six are female, thus contradicting the earlier assumption of male gender predilection and questioning the role of sex hormones in its development.…”

“…The FCCH is one such benign tumour with intriguing clinicopathological features, reported in 13 cases of TSC since 2012. [ 1 2 3 4 ]…”

“…Of the 14 reported cases (including ours), six are female, thus contradicting the earlier assumption of male gender predilection and questioning the role of sex hormones in its development. [ 1 2 3 4 5 ] Being a recently described rare entity, its pathogenesis is unverified. Although mutation in TSC1/TSC2 leading to uncontrolled cell proliferation, explains its hamartomatous nature, it fails to explain its occurrence in patients without TSC and its unique histology.…”

Clinical, pathological, and molecular correlation of folliculocystic and collagen hamartoma: A new potential diagnostic criterion for tuberous sclerosis complex?

“…Including the three cases described herein, 18 FCCH patients have been described worldwide to date; of them, 16 (89%) had a clinically definitive diagnosis of TSC (Table 1). 2,3,[5][6][7][8][9][10][11] This suggests that there is a strong association between TSC and the presence of FCCH. 2,5,7,11 The two patients with apparently isolated presentation of FCCH lack any clinical data suggestive of TSC at 6 2 and 19 4 years of age.…”