Phylloid Hypomelanosis and Mosaic Partial Trisomy 13

Abstract

Background: Phylloid hypomelanosis is a rare neurocutaneous syndrome characterized by a pattern of hypopigmentation consisting of leaflike or oblong macules reminiscent of floral ornaments. Associated extracutaneous anomalies include cerebral, ocular, and skeletal defects. Recently it has been suggested that this phenotype originates from mosaic partial or complete trisomy 13. We report clinical and cytogenetic data for 2 cases. Observations: A bizarre pattern of multiple leaflike macules was noted in 2 girls with mental deficiency. In patient 1, additional anomalies included syndactyly, clinodactyly, trichomegaly of the eyelashes, low frontal hairline, and several pale pink telangiectatic macules. In patient 2, epileptic seizures, dental malposition, oligodontia, preauricular fistulas, scoliosis, tethered cord, and syringo-myelia were noted. A diagnosis of phylloid hypomelanosis was made in both patients. In both patients, blood lymphocytes showed a normal karyotype 46,XX; however, fibroblasts derived from lesional skin demonstrated tetrasomy of chromosome 13q21-qter in patient 1 and trisomy of 13q22-qter in patient 2. Conclusions: These 2 cases lend further support to the concept that phylloid hypomelanosis is a distinct clinicogenetic entity that should no longer be confused with pigmentary mosaicism of the Ito type. From a comparison of our cytogenetic findings with those documented in previous articles, we infer that phylloid hypomelanosis is most likely related to the 13q region.

Phylloid Pattern of Hypomelanosis Closely Related to Chromosomal Abnormalities in the 13q Detected by SNP Array Analysis

“…Inflammatory lesions reminiscent of hidradenitis suppurativa have been previously described in 1 patient only [10]. It is still unclear if this condition is related to mosaic aberrations of the chromosome 13.…”

Phylloid Hypermelanosis and Melanocytic Nevi with Aggregated and Disfigured Melanosomes: Causal Relationship between Phylloid Pigment Distribution and Chromosome 13 Abnormalities

“…The cytogenetic analysis of the peripheral blood lymphocytes revealed chromosome 13 abnormalities. Happle [3] reviewed 6 cases of hypopigmented phylloid patterns with cytogenetic findings, and has recently reported a further 2 cases [5]. Dhar et al [6] described a case of phylloid hypomelanosis with tetrasomy 13q mosaicism.…”

“…Eight of the 9 cases were associated with aberrations involving chromosome 13, although 1 was related to mosaic trisomy 14 [3,5,6,7,8,9,10,11]. An examination of the blood lymphocytes and of skin fibroblasts in the previous cases revealed 46,XX/47,XX+13 in 2 of the 8 cases [7,8], 46,XX/47,XX,+der(13) [9], 46,XX/47,XX,der(13)i(13)(q21qter) [5], 47,XX mar. rev.ish enh(13)(q22qter) [5], and 46,XX/47,XX+inv dup(13q21.2) [6] in 1 case.…”

“…An examination of the blood lymphocytes and of skin fibroblasts in the previous cases revealed 46,XX/47,XX+13 in 2 of the 8 cases [7,8], 46,XX/47,XX,+der(13) [9], 46,XX/47,XX,der(13)i(13)(q21qter) [5], 47,XX mar. rev.ish enh(13)(q22qter) [5], and 46,XX/47,XX+inv dup(13q21.2) [6] in 1 case. On the basis of the cytogenetic analyses, Happle [3] suggested that phylloid hypomelanosis rather consistently indicates a mosaic trisomy 13.…”

Phylloid Hypermelanosis in a Child with Psychomotor Delay, Cicatricial Alopecia, Hearing Loss and Polythelia

“…While phylloid hypomelanosis is linked to trisomy 13, the cause of phylloid hypermelanosis is more obscure (5,(7)(8)(9)(10)(11)(12)(13). We describe here a case of phylloid hypermelanosis associated with mild developmental delay, cicatricial alopecia, hearing loss and polythelia.…”